^^^^ THIS ^^^^
e-collar is to reinforce your command. If they don't understand the command they cannot understand the reinforcement so can't connect how to respond to the stimulus. Also, if/when you purchase, don't buy any e-collar that doesn't have at least 100 settings. The cheap ones at pet stores have 10 - 15 settings and you'll find #4 doesn't do anything and #5 makes them squeal.

These are the things that give e-collars a bad name.
^^^^ and THIS ^^^^
Best thing you can do for your dog is train with other puppies his age with an instructor who understands working breeds. Some people & puppies do OK at pet store classes, but I can't recommend them for a feisty Doberpup.