Do not appear taking him too seriously.

 

Whenever he is acting up, tell him to focus on the task at hand and solve the problem by applying his mind and thinking it through. If he feels his parents are the problem, tell him to stop distracting himself ("You may have some difficulties right now. But I can assure you that your mom and dad are not your problem, and we are here to help you.  But you need to be honest with yourself. You are good enough. You are worthy of your effort. Always show respect because you tell people you always expect respect from them. We show you respect by talking in a calm voice, and you do the same.  With a smile, you can say a lot of things that you cannot say with a long face.  You may have a lot of feelings and emotions right now. It's OK to have feelings. Do feel it. But just feeling it is not enough. Staying emotional is a liability. Use the upper layers of your brain and think of the words you are going to string together to express what you want. Feelings will only silence you because they impair your mental ability.")

Do not react to him too quickly, act dumb and slow. But show that you care.

Make sure he has everything a teen needs, starting with the furniture.