Terriers are barkers, that's a given. lol. They are VERY vocal and the yappiest of any dog out there. If you don't want a dog that barks a lot then a terrier probably wasn't the best choice. BUT with proper training you can teach him to control it sometimes.

But he just sounds like he's going through his rebellious "adolescent" stage where it seems all the tricks and training go out the window. That's not the case, in fact its when they REFUSE to listen to you that you know they really do know the commands, so be proud of yourself. He'll "grow up" one day and everything will just click. Until then -- PERSISTANCE!! Don't slack in training, and don't loose your cool, even if he doesn't listen!