Thank you Betty for that information.
clapping your hands and other noise distractions are just interrupters that will stop the behavior in that instant , but not likely to stop it long term.
Chewing is usually from boredom or stress and since you describe his personality as outgoing I don't think stress is a factor.
I might invest in toys that are mind stimulating such as dog puzzles where he has to figure out how to get the food out by moving puzzle pieces around, I might try the buster cube for his meal time rather than a dish and try to do more training sessions as this also tires a dog's mind, which is very different from exercise of the body.
I would also firm up the leave it command by starting over in training it. When a dog does not listen to a command when you give it, it just means it was not taught long enough before it was used in a real life circumstance.
I would also keep him contained when you cannot watch him. At this time we know he will destroy something if left to his own devices, so basically we are setting him up to fail by letting him have free run without being watched.
I am not sure what type of training you are doing but clicker training works very well with pups. If you would like I could send you some links on how that works. It is a positive method.
Because of his age, I would train several times a day for short periods, 10 to 15 minutes and this can be while you are cooking dinner or watching TV, anytime can be training time:)