What is the proper way of dealing with Senior NCOs as a Junior Officer?

Brother, I'm happy you brought this up because it needs to be addressed. I haven't had quite the issue you have with it, most likely because I spent 11 years as an enlisted Marine before going to Army OCS. The problem you mentioned is not nearly as prevalent in the USMC as in the Army, by the way. Here's the deal. The difference between a commissioned officer and an enlisted member is a difference of kind, not of degree. As a SSgt of Marines I encountered plenty of officers who were younger/less experienced than I was, but showed the proper deference to their rank nonetheless.
With that said, in my opinion the most respectable person in the Armed Forces is a senior NCO (with a CW5 being right up there as well). Learn from them, show them that you appreciate their wisdom and their willingness to share it with you, but don't tolerate anyone's refusal to acknowledge the rank structure. My take on dealing with senior NCOs (including a SGM/CSM or a 1SG) is this: If a senior NCO suggests to me that I should do something, I will almost always do it. If the senior NCO orders me to do something, I will NEVER do it. Please try to fix the relationship between you and the NCOs and get it on proper terms as soon as you can, because no one can teach you more than they can.

You need to take a deep breath. Take an inventory of the situation and move forward. You next set of moves will make or break you. First, you need to be straight. You need to be able to lead. You need to set the example. Your PT should be straight. You should be qualified on all the platoon's equipment and weapons. You are at least 15 minutes early and you don't leave before your platoon. That's the minimum. You get those skills from your platoon from your soldiers. Next your part of a team. You are the leader but your part of a leadership team. I would expect you have made sure all of your statistics are good (APFT, weapons, etc). Your NCOERs and awards are done, correct, reflective of the individual and on time. Also you are doing your counseling in accordance with the regulation. If any of this off fix it first. Fixing it will set the tone. It will take teamwork to get right. Participate in nearly everything.

Doing your inventories correctly and doing your maintenance correctly sets the tone.

Being a team, means building the relationship. Go to lunch, go for runs, something. Build the relationship. No parties. A beer now and then is good.

Build a relationship with your CSM and your 1SG. Things will start to change.

If all that doesn't work then bite, but you need to be straight first.

Be humble, be ready to learn, stand your ground.

LT Garcia, welcome to the private rank of the Officer Corps :) That being said, tongue in cheek, here is the bottom line: It is unusual for a senior NCO (at least one worth his or her salt) to truly be insubordinate. The Senior NCO may challenge you, and you might feel that the NCO is being insubordinate, but take a huge breath and ask yourself the real question: is this NCO truly being insubordinate or are they attempting to challenge you as a junior officer? I think the junior officer that tries quickly to establish that they are in charge, but ignoring the wealth of experience that is part of the Senior NCO, is the one that gets in trouble with this particular scenario. I had an incredible Senior NCO when I first entered the military, and as I was there to learn, he was there to teach. Consider taking that approach (first, because it is right and second, because it truly recognizes that these Senior NCOs know what they are doing). If, on the other hand, you have Senior NCOs that have not been successful in their position, and they truly are merely treating you inappropriately, because you are the new kid on the block and a junior officer, then I would click their heels together. Although, never an impossible scenario, it is unusual for more senior officers to ignore the importance of respect by all, let alone the senior NCO showing respect to the junior officer. I truly wish you the utmost success in your future. Work with your NCOs, learn from them, and at the same time, mentor them. They usually deserve it and will ultimately have your back in an urgent situation.

Sir at no time should you be disrespected by anyone regardless of rank. That's sheer professionalism on all sides. I would ask is this person giving you "tough love"? With that I mean, is he mentoring you, and monitoring your mistakes but taking a firm (maybe too firm) look at you? Tough love could be seen by the person getting it as rude and down right disrespectful, but all this person's trying to do is take lessons learned, reinforce them, and ensure that you don't forget them. I've had PSG's and 1SG's KNEE DEEP in my backsides, but it wasn't in malice; it was because they saw me making mistakes that are easily corrected but rather than give me a 4856 or worse, let's make him sweat (not a smoke session) a little, for a little while and see if he learns what he did wrong, how to correct it, and how not to let it happen again. Stuff like that goes a long ways for when it becomes YOU as the leader and you see someone doing the exact same thing you did years before. But on the flip side, you always have that one, who doesn't know his role, yet knows his rank. I'd say step back and really look at what's being done. Is it really offensive or hard teachings (sort of like a DS)? If it's hard teachings, talk to the NCO one on one and ask what can WE do to make things better? You know you're in change overall, but in order to make the team, it takes both of you together to make it happen. That NCO should be able to tell you everything you need to grow and have the platoon grow with you. If not, check him. You're in charge.

First off, you do have command authority as a Platoon Leader. If anyone told you otherwise, they were smoking something. Second as most of this thread responses imply. You have ownership of a lot of that relationship. You have to prove yourself, but you won't do that by locking some NCO's heels on some minor point.

The purpose of a Platoon Leader having a Platoon Sergeant is not for that NCO to be subordinate to the LT, although that is true by regulation, but more importantly so that the LT can be taught, coached and mentored by that NCO on what right looks like.

I believe it was Machiavelli who wrote, 'keep your friends close and your enemies closer'. Build your PL/PSG or OIC/NCOIC relationship from the point of YOU learning. Show respect and demand it in return.

CSM J. Fenton

1LT Garcia, this question is tricky and there are a lot of rabbit holes to dive down. Without putting the cart before the horse I would say that regulations cover almost everything and interpretation is for the JAG. I've been a Senior NCO for sometime and served as the NCO for 0-1 through several 0-6 (non-command slots). I've always had a better relationship with the Field Grades Officer (FGO) then I have the Juniors. The biggest difference I will say is when it's time to come to the table, generally, the FGO has their work completed and can provide detail and/or synced plan. They take suggestions and brainstorm ideas and way's to. The last few ROTC cadets I've worked with were over-whelmed, it seemed, by the pace and didn't talk with commanders enough to get a good intent and end state and didn't understand MDMP or how to prioritize. I've had Junior Officers that wanted to make the PT schedule for the PLT, is that really their job?
I wanted to address a term you used in your question of "outrank". You can possess command authority of an element, as do PSG, Squad Leaders and Team leaders IAW AR 600-20. If you notice two other areas exist Chain of Command and NCO Support Channel. This is a parallel effort and not a hierarchy of betterment or priority. I think these two ingredients when used correctly together is critical to the mission and welfare of the Soldiers.
One has to realize that as Senior NCOs we've had a creed instilled in us that most can repeat after their time in the Army has closed. We also know the root word of Sergeant is servant.
We take an oath of servitude for the people of the United States and inside that oath it specific implies "and of the officers appointed over me".
Article 91 and 92 cover a lot of what insubordination is and JAG has to define that better to your local situation.
To talk a vignette I've recently had. We run a Junior Officer Professional Development program. I've had two LTs come to my office and one insisted that I stop what I'm doing (BN plans) and review her slide deck then. It didn't happen and the XO told her to leave as the conversation she started to have with herself carried down the hallway.
The second LT sent an email with the slides and ask when I have time could I assist her in developing the slides and check the slide-ology IAW BN's liking, just let her know when to come by. She hit her target.
Generally speaking, I don't know of many Senior NCOs or NCOs that want to see a Junior Officer fail or be un-empowered in front of troops. We all move on and honestly I want to do the best I can for my organization in a collective manner. I know Junior Officers hold a precious key of the future of this organization as being Company-Bn level Commanders. I'm part of their rudimentary base and they have to learn how to trust me, but they also need to learn that I'm going to do what's in the best interest of the Soldiers, the unit, and the greater objectives and if I feel request being made are unlawful or due to poor performance or preparedness on the behalf of the individual ... well I'm not always going to play the nice submissive servant, as I know they would probably want to hammer my ass if I came to the table only half prepared demanding they finish my work.
When assigned the role of a PSG; I'll listen to the PL and follow the order.
Using the example of PT in the PLT. I've been to the Master Fitness trainer course and the Company Commander wants to meet the BN mark of 260 for all Soldiers. The PL gives the mark on the wall and I do my due diligence to get the Soldiers there with a PT plan to accomplish the weak points and build in success. If other PSGs hit the mark and I didn't then perhaps this shouldnt be marked Far Exceeded Standards on my eval. If I did hit the mark of all Soldiers get over 260 but didn't get a 300 on my PT then perhaps Far Exceeded should be.

We're all still learning and when that process stops then all the problems being.
This probably wont be a popular answer and a lot of people probably wont read it all the way to this point but this is my view and I care to do the best by the Soldiers and the Unit's Mission.

Junior means you don't know it all. NCO's are subject matter expects! Learn from them all you can. Present an empty cup and they will fill it! Finally, never lower the bar on discipline or tolerate disrespect. Remember, if you lower the standard, that becomes the new standard!

LT.. at the end of the day- you own all of the relationships you will ever make in your career. The good ones will be powerful and the bad should be developmental. Make this one developmental and learn from it. Understand that with limited exceptions most senior leaders want to be on a winning team with others that they know can take them to that goal. Senior NCOs and others with different relationship agendas may be distracted from working with you to develop a successful team and one key to reorienting them is to demand and deliver success in yourself and your team. Establish strong team goals, achieve them, and celebrate your team accomplishments. Earning respect is the best alternative to achieving your goal, but respect can't be achieved through a verbal order.

What you can do in the meantime is give yourself some breathing room to earn that respect. I recommend talking with other Senior NCOs and getting their take on some reasonable ground-rules, then let the person you are having a problem with know your issues with his behavior and communication style. Establish your ground rules and let him know that you respect his experience and that he has your full support. If that fails to resolve the issue over time then you are dealing with a bad apple and you will likely need your commander's support to resolve the issue.

At the end of the day, you need to be prepared to lead, fight, and win with a cohesive team. Building that team should be your principal priority and these are the lieutenant lessons that will refine your own leadership perspective as you continue to develop. Don't disregard the challenge and if possible don't simply "order it to stop". See this as a weather gauge on your path to disciplined leadership. If you take this hill- you'll gain long-term confidence.

I've seen the "Goat Locker" self-regulate on this more than once. At the end of the day, I think if you show respect for their experience and knowledge...most NCOs will go out of their way to mentor a new officer.

If you need to ask this question you need to speak to your supervisor. My 25 years of army service taught me how to be effective as an NCO... Young officers learn by being a officer from day one. Questions see your platoon Sergeant... Also know the difference between NCO and Officers business...