Thanks for the additional information. It is helpful. I'm really not sure of what credentials the person had that gave you some of this information. It rally goes against what most trainers and behaviorist know. However, let me go over some information for you.
First off, the dog needs obedience training. That is a very large part of the problem. The ultimate goal will be to get her into a class, but she needs training and now. The following site is helpful for teaching YOU how to train your dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
Additionally, everyone in the family should participate in training, but you can start other family members helping with training once she is responding well to commands from you. This will help her see you as the boss and once others start working with her, them as higher in the pack than her. If she feels she is the boss, then she feels that she needs to reprimand people that do things she doesn't like and feels she needs to protect you since she sees you as her person, thus the growls and even nips to reprimand.
Once you are the boss, she should not feel like she is the protector and should not feel like she has the right to reprimand everyone. So start the obedience training. I suggest using hot dog slivers or liver slivers while training since they are high value treats. Each time she obeys a command even if for a treat, it does make her a little more submissive.
Dogs that are allowed on furniture (even if put on the furniture) tend to feel that since they are elevated to your level or higher if on your lap, they mentally feel elevated as well in the pack order and thus are the boss. Keeping them on the floor can help lower them mentally back to a submissive position in the pack. So the first thing is to not allow him higher that the humans or even on the same level. Attach a leash and use it to remove him from the furniture. Give a correction in the form of a quick tug and firm "NO" when he attempts to get on and a treat when he starts not trying to get on the furniture. Thus you are providing negative reinforcement for the getting on the furniture and positive reinforcement for the desired behavior (not attempting to get on the furniture).
Now when a dog is misbehaving and you go and show attention and tell her good girl in a soothing voice, you are showing the dog positive reinforcement. In other words, the dog likes being told she is good and the attention, so she will learn to exhibit that behavior to get the good attention. So I would stop that techniques entirely.
Instead, when she exhibits behavior that is unacceptable, give her leash a little tug to break her concentration and tell her NO in a low toned voice. The tone is important as it is more growl like to indicate a reprimand. Now the other part of this is that after a few reprimands she should stop the growling. As soon as she does that, reward her for not growling with nice calm praise like "good girl" and a tasty treat. This is behavior modification. She'll learn that she gets good things when she acts in an acceptable manner.
The same techniques can be used for her barking at windows and passing strangers though many owners get a citronella collar so excessive barking is immediately corrected with a spray so they learn quickly to not bark.
I also want to give you another technique used called BAT.
I hope this information is helpful to you and you are satisfied with my response. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have .