Hi Diane. I am going to suggest you PM luckypenny or one of the other members who have tons of experience with training. You could even try tenderfoot. Sounds to me like Simon and Jessie are just being rambunctious. Simon isn't baring teeth, is he?
Just have to say something about that "pit" comment- as a new member SamIam you will not know that most of us here do not place labels on dogs because of breed so I will excuse you. Some of our members have pitties. They are much loved, gentle members of their families. We blame the owner - not the breed. Why even put something like that in the equation?
As for labs - I have one. There are moments when she has felt threatened because of an incident that happened to her when she was younger that she could very easily injure another dog.