Dogs growl and bite to take an advantage over the other or to become a ruler.
Dogs want to avoid fighting with others as much as possible, so they start by growling first. If the growling doesn't work much, they start to wrinkle their nose, lift their lips, show their teeth, and snarl for more terror. If it still does not work well, they will take an aggressive action of biting. These come from the dog's containing instinct. Dogs with strong containing instincts are more likely to intimidate and attack.
To stop growling and biting, you have to retrain them collectively. Dogs that lack basic training or are not trained to be submissive to humans can easily become intimidating and aggressive toward humans and their owners.
As a training method, it is effective to pretend that you can't hear the growling. You should not yell at them or try to suppress them with corporal punishment.
If you do that, they will start to be even more intimidating, thinking they have to take action before they get hit.
By being ignored, they think that even though they are trying hard to intimidate, you do not respond at all, and understand that barking is ineffective, and you are stronger than them, and they will stop the intimidating.
If ignoring doesn't work well, you should use the punishment method. (What is the punishment Method?)