Okay, the person that said WHEN THEY HOLD their puppy's MUZZLE the puppy gets MORE aggressive or lets say doesn't like it.
With my trainers......you can simulate what a mother dog does by LIGHTLY taking your halfway closed hand and lightly
stroking their muzzle as a mother dog will put their MOUTH over a puppy's to show the dominance or whatever WORD you'd like to
choose.
It may take time.....another thing is the tethering, along with sitting behind your puppy trying to run your hand LIGHTLy along
their muzzle, head and body. TEACHING them you're #1 and when they sit still aka "good settle" (or whateverpraise you like)
they get rewarded and more attention for staying calm.
you can also try having them sit next to you whileyou sit in a chair.
i have in 10 yrs with the same trainers seen wonders even with young puppies that were very dominant
eventually melt like putty and learn.
Biting, nipping, jumping...........all NORMAL behaviours
just as a toddler does similar things....all NORMAL
it's up to US though to give the right direction of guidance to what is and isn't acceptable WHILE practicing
love, patience, and a darn good sense of HUMOR
hang in there......puppies go through various stages which is all a part of growin up.