Arghhh Rage!!!

Seriously annoyed with this now. Having major issues trying to paint the weights for the character. Everytime I take the influence off 1 part of the arm it moves to another part of the arm and its a vicious circle I dont know how to get out of.

The orange circles show the points I'm trying to remove from being influenced by the left arm, But I can't for the life of me get it to work. Going to ask Paul tomorrow if he's around to see if he can help me out because this work needs doing asap and I'm worried how much longer its going to take :/