Welcome from Spain!
Whatever you do, do NOT let him behave that way towards you, you've got to show him that growling or using his teeth on you is NOT okay.
Make sure to never step back, act scared, or give him space whenever he does that, as you'll be reinforcing the behaviour.
Stand your ground, correct him if needed, and let him know that's not acceptable.
I don't like positive only trainers for this breed, they are tough, intelligent, and can be absurdly stubborn. They THRIVE on strong leadership.
I would do the same things the rest have mentioned, I would try to make the crate a fun place, not the place where all fun stops. Feed him inside his crate, put him inside for a short period of time, and after you let him back out fuss him.
He's going through the terrible Doberteens, just keep training, don't let him bully you, show him the pack order, and you'll be fine!.
Hang in there!! It does get easier, keep us updated please
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