Generally it is people he knows but if he has something to say he will say it regardless of who is there. You can't seem to reason with him.Constant warnings have no effect.
Apart from that he does have his hectic 5 minutes and won't settle, when his 5 year old brother acts older than him, but i think you expect that sometimes??
Hello and Thank You for responding. Your son seems to be having difficulties managing his emotions. He is unable to ascertain the boundaries between right and wrong. It sounds as though you have done all that you possibly can to assist him but with no continuous luck. Therefore, I would suggest a behavioral counselor that can be recommended by your son's pediatrician. Your son needs a neutral person that he can express his feelings with. He also needs to learn coping and intervention strategies of what to do and how to behave when things do not go his way. He also needs to learn how to be more respectful toward adults possibly through a series or role playing exercises with the counselor.
Hope this provides you with a little direction and insight. Have a great day.