Your problem is easy to cure, Mudduck. You have to learn how to play the bass!
I'm messing with you a little, but basically, that's what you have to do. You have to use your hands to stop the other strings from vibrating. And that just comes from learning good techniques. If all you can line up for a teacher is someone who plays guitar, I think it's OK for a beginner to learn from a guitarist, but you will want to get a real bass teacher when you start to figure it out and want to get better.