The reason most dog trainers, books, and videos are not effective is that they don't go into enough detail. Dogs respond to the subtlest details of our interactions with them. Generally these are things that have no meaning to people, but mean a lot to dogs. To change dog behavior requires that you find someone that recognizes this and can show you exactly what it is in your interaction with your dog that your dog is responding to that is not getting you the result you want.
This becomes particularly important once the trainer shows you a technique and you have had the opportunity to practice. Results come from picking up on the smallest clues sent by your dog as to how effective your interaction is at producing the result you want and fine-tuning you technique based on this continuous feedback.
You can teach your dog new behaviors from techniques you learn in books and videos. The phenomenal video on how to muzzle train your dog below is a perfect example. Changing an existing behavior, such as fear aggression, requires a different approach because you have to work to extinguish the old behavior at the same time you replace it with a new behavior. This is much more complex and there are many ways it can go wrong. To do this you will likely need someone that can show you how to respond to your dog in a way that is going to reinforce the behavior you like while at the same time discourage the behavior you don't like. Since every dog and owner are unique, it helps if the person is a behaviorist that creates an approach that will work for you and your dog based on what you are capable of and what your dog responds to. This is what distinguishes a behaviorist from a dog trainer.
This App takes this into account. I will not be offering training advice on how to change specific dog behaviors because the medium of written words and even videos is not suited for this task. Instead I will be offering general guidelines to help you start to change the way you view your relationship with your dog to give you the ability to see things from your dog’s perspective. This will give you insight into why your dog behaves the way she does in every situation.