If you are suspected of an offense, you have the absolute right to remain silent and to consult with an attorney. These two rights are different. The Article 31(b) rights advisement does not have to be in writing, and you do not have to sign anything to waive your rights. Your rights can be read to you verbally, and you can waive your rights verbally.
If you desire to exercise your right to remain silent and/or to consult with an attorney, you must explicitly state your desire to do so. For example, if PMO or your 1stSgt suspects you of misconduct and asks you “What happened here?” it is perfectly okay for you to respond with, “I respectfully wish to remain silent, and I would like to see a lawyer.” Even after you see an attorney, you still have the right to remain silent and not make a statement. Whether you make a statement is up to you, but you should speak with an attorney to discuss the pros/cons of making a statement before you do so.
If you choose to make a statement, whether written or oral, it can be used against you. This includes conversations with law enforcement, your chain of command, friends, family, on social media, and via email. Any statement you make must be truthful. If any part of it is false, you may be subject to further prosecution for making a false official statement.
You do not have to consent to searches or seizures of your property. For example, if PMO asks you, “Is it okay if we search your room / look at your iPhone/ take your computer/ etc.” or “Do you mind giving us a urine sample” it is okay to refuse and to require them to get authorization from your CO (similar to a civilian warrant).
During an interview, law enforcement officers are permitted to lie to you and to embellish the facts in order to get you to incriminate yourself. This means that they can say your accomplice confessed when he did not, that they have your DNA when they do not, that they have you on camera when they do not, and many other things.
Law enforcement officers may offer you an opportunity to take an “exculpatory polygraph” to prove you are telling the truth. Polygraph examinations do not produce reliable or accurate results and polygraph validity is scientifically weak. Very often, these polygraph results will indicate deception or are inconclusive. Just like remaining silent and refusing consent, you have an absolute right to refuse a polygraph examination. You should speak to an attorney to discuss the pros/cons of polygraphs before you submit to an examination.