Publicly Bashing Leadership

Coming up as a second generation service member, I have often heard that we (the armed forces) have a restricted 1st Amendment. I have never sought and saw this in writing only hear say. My question is, is there something in writing that would prohibit a soldier's right to verbally attack or disrespect the president or any other leadership? Also in the same ball park can a soldier be punished for addressing the president informally. ie Obama or Barrack instead of President Obama? My logic is you wouldn't call Your BN CDR by his first name so why address the top dog any less than by the title he has earned. Regardless of your personal opinions.