Mouthing and arousal biting, help please!

Happy new year to all! I hope you've all had a great Christmas and I hope it continues into a blessed new year

Right anywho,

I really need advice on mouthing and arousal biting in adult dogs, has anyone got any experience dealing with it? We had a bit of an episode over Christmas, a friend's twin girls were playing and the dog bit one on the leg. She was over excited, and I'm unsure if she used force or the girl pulled away and it it hurt more because of this (if that makes sense) I wasn't there, stupidly I let a friend hold her on her lead while I was in the house and not knowing the dog he relaxed the lead to extend further than I would have.

she does it to my 8 year old when he plays but he's getting used to dealing with it now. We seem to have curbed it with adults as she hasn't mouthed us for a few weeks. But obviously worries me with children as I can't trust her around other friends or family children. Which I think is unfair for her as she obviously loves being around people. I really don't know how to get her to stop, all Google has come up with is reasons why they do it and no clear answer on how to stop.

I've had her maybe 5 weeks now, rescue bitch and she's about 19 months old

If anyone can help I would really appreciate it!