gsp training help if you can
 

my gsp is 2yrs old i got her at 1.5 yrs old she is house broke and obeys most commands . she lays down on her back and spreads legs when she gets in trouble,especially if you raise your voice which i think means she was beatin before. she gets nippy if you try to pull her off the couch or if you put ker in kennel (not always though just sometimes). can this be fixed and is she too old to train if not where do i start, and do i use a shock collar. any help would be great.