Dana, most puppies are too busy to be affectionate, give him time to grow and settle. Frustration comes from not knowing what to do. Your instincts are right, he cannot be allowed to interact with people this way, as habits form very early. Remember he has been relating to Mom and litter-mates with his mouth. They all liked this way of interacting which comes natural to dogs. Now he has to learn people don't like it and have thin, sensitive skin. This is why rough-housing is a bad idea, it encourages pups to use feet and mouth to interact with humans, so sends the wrong message and is confusing when you are trying to teach him to be gentle. Your frustration will subside as you become clear on a course of action and start to see the results. Have fun with the process, they grow so fast!