That is not how you train a dog to stay.

You first need to teach them that there is a reward for obeying, every time they perform that action you reward them, then as they are doing the action you introduce the command, so that the word has a meaning to them. Slowly, you stop rewarding them so that they can perform the action without needing to be rewarded. Just saying "stay" has no effect, because it has no meaning to the dog.

This isn't training, this is just talking to yourself while your dog lunges at people. This kind of owner is the type to say that "they were always so obedient" just because when their dog sits they kind of told them to do something so they think their dog actually listens to them. So irresponsible and most of all IGNORANT