Training for your dogs will help.....let your friends pet them, play with them etc.....putting them outside just reinforces the idea that they shouldn't have contact with people. If you need to.....put them on a leash. Those types of terriors have excellent personalities (with people...generally) if well socialized. I love all those bull-type breeds.....and won't have one anymore until I can watch them like a hawk until they are well into their adulthood.