About a year and a half ago my familys golden retreiver died a dog that need virtually no training and was practically perfect in everyway. We then decided we wanted another dog so we went to the pound were we got a dog that was supposibly German Sheperd/Golden retriever when we first saw the dog she was well behaved allthough a little hyper which we figured was from excitmenet. When we bought it home we noticed the dog had moments were it went completely outta control running around the house and sometimes bitting us especially(getting as bad as to be considered an attack) jumping on us and growling especially when shed get into moments were she bite our feet. Some other people(including professional trainers) say are dog look like it has other breeds in her I did some reaserch and figured out that she looks exactly like and acts like a rottweiler making me 99% sure she is part that breed. We we're not ready for this kinda dog. The problem with the dog is the random attacks for no reason,the constant bitting and jumping on (which scratches us), and when new people come or people she hasnt seen in awhile she will jump and bite, and when we take things away from us she growls and bites and sometimes attacks us. We have given this dog constant love she always wants to be with us we potty trained her,she knows sits and downs, and she knows how to use the invisible fence(which took her all of maybe three shocks for her to know what to do). We've tryed bitter apple, saying no and ignoring, putting her to the ground and closing her mouth, distracting her with something else, none of those stops her from bitting us or other people. She is about 6 months old we've had her for three and a half of those months(some other people had her but returned her because of the biting we were not aware of this) and were just afraid shell hurt someone and have to be put down she is very smart so smart she can bash open the front door and run out(the invisible fence stops her from just running around free but shell bash through to greet us or a new person) but if some ones there she could attack them with our us being able to stop her.I realize we prolly shouldve never got the dog but we didnt know any of these things about her and we dont wanna return her because she is so attached to us and will even cry when were not there and what not. Also I realize some of you are against invisible fences but she already uses it its 2 late to change she doesnt get shocked anymore she knows the boundries and shes only taken a few shocks(which i have felt and dont hurt so much as surprise you) and she wouldve prolly dug, climbed up, or broke through a fence. Plz any advice at all and one method I was considering was adjusting a dog whistle to make it hurt her and use it when she does behaviors that are unacceptable. Im extremely desperate and the whole family will work together to do anything. PS:she is not spaded but were gonna and we have taken her to an obdience class that did really nothing cause she was to busy and distracted by the other dogs to misbehave and there advice didnt help us.