Hi and welcome to YT
!
I've never heard of "angry" yorkies, nor have I experienced that at all. They're super happy, fun, lively, unique little characters though. I wouldn't call my 3 yorkies yappy, but they are great watchdogs and will bark at strange noises - as well they should, that's their job and that's using their voice as it should be used.
I do think they are notoriously tough to potty train though - yup! But some people do get lucky and their yorkies potty train just wonderfully.
Just remember that *all* young puppies, regardless of breed are mouthy, sassy, have little manners, and of course no training...
This thread might be helpful:
http://www.yorkietalk.com/forums/gen...ent-guide.html