I don't have trouble with the dog running up on people when I don't want, but rather, I have the problem that people approach the dog when I don't want them to. My Zeus is easy to control until that happens.
When it does happen I tell them the dog's in bite training and that it's dangerous to approach. That cures most of them but for the kids.
I tell them that the dog's just too big at 6 mos. now and that he doesn't know his own strength even though he's friendly. That stops most of them.
But once in a while I'm going to be chatting with someone I meet while walking the dog. In that case, not only do I not want the dog to jump up on someone, but also, I want to have some peace so I can chat. In those cases, I make the dog sit, lay down and step on the leash about 2 ft from the collar.
Works every time, but for a bit of whining if the conversation goes longer than just a couple of minutes.
Step on the leash a short distance from the collar. No jumping possible then.