Keep a lead on him in the house. Put a dog gate in the doorway to your lounge so he doesn't start scratching at the door. When he chews the sofa, get up, grab the lead, don't say anything to him or give him any eye contact, take him out of the room and shut him out. Sit back down, still don't look at him. Give him a few minutes, let him back in, again without saying anything or looking at him. Be consistant and do it every time he chews.
The message there is that he doesn't get told off or get any attention for being naughty, but if he chews the sofa he gets put out of the room. If he can behave he can stay in with you. Make sure you tell him he's good if he's in the room and not chewing the sofa, and give him something else appropriate to chew on.
Also, get his mouth checked by the vet to make sure there is nothing hurting him and making him chew.