First time Lab owner looking for some training advice. I have a 16 week old female chocolate puppy. The issue that I'm having is that she a major biter. I know labs are mouthy but its really becoming a problem. During play she will often bite hard enough to break skin. It seems to be getting worse now that she is latching on and won't let go. We have tried several techniques I found on google searches such as: "yelping", going limp, replacing my arm with a toy, bitter spray(utterly useless) and even shaking a soda can full of rocks. Some of these techniques seem to work well for a day or two, but after that she just ignores it and continues to bite harder and more frequently. Please help!