HELP!! HELP!! (staffy mastiff cross) puppy 5months 3 weeks old snapping/trying to bite please read?

we were told to follow the instuctions that the rescue centre give us for e.g the puppy climbed on the couch before and my dad was anoyed so he draged him down NOT vilently then the puppy kept getting back up as my dad reached for his collar the pupp tried to nip/bite him and started scratching at the couch and cushions and going mega hypo. is this an early sign of aggression or has my dad used the wrong techniqu or is this just what some pupies do