Hi there! Welcome to YT!
When Lucy used to bit we would tell her 'no'. If she kept doing it we would give her a time out. We put a high gate up on the kitchen door so she was then shut away from us. In the end I think it was a combination of that and growing out of it. I wish I had known about bitter apple when she was a pup as it does sound a really useful deterrent to stop them doing it in the first place