@sharronhurlbut:
Training with treats will work, if you take it slow.
Clicker training works as well.
I was going to say the same thing. I would carry a treat bag with me, and a clicker when out on leash. Use the clicker to mark correct behavior, i.e., sitting calmly while another dog passes. If my dog gets snarky on leash, I promptly stand in front of him, and put him in a sit/wait with a focus on ME (not the other dog). if he persists, I simply become a "goalie" and continue to block his path, get eye contact, and again, get a sit/wait.