snappy friends

Mambo's not lucky - so many dogs we're meeting on our daily walks want to snap him that I feel really sad for him he can't get any friends! Not including few obvious cases when the other dogs are just aggressive, I'm sure it's Mambo's attitude, because he's very nosey and pushy - bit of nose and back sniffing with tail waggling at the beginning and then he's off to jump on new friends' heads! Don't know what to do to stop him acting like that, of course he's not aggressive when he does it but it means that he can't even have a proper 'hello' with most of the dogs because they don't like him putting his paws on their heads so they want to snap him or at least are not longer interested...
yesterday we met his friend rottie who we met at the charity dog show few weeks ago - they were happy to see each other until Mambo jumped on poor rotties head, of course rottie told Mambo off by growling at him - it was by Morrison's so few people jumped once they heard the nasty 'dog fight sound' and saw the staffie and rottie standing next to each other of course they were fine after that, no harm made, waggling tails again, but i didn't let Mambo to come closer again.

any ideas on how to teach Mambo to act a bit better (and calmer!) when meeting other dogs?

Aww poor Mambo, that mad me sad when you said he has no friends!! He is trying to make some, but well, not getting very far by the sounds of it! When Moo is on lead she often does it, but when she is off she doesn't do it at all, not much help there really. I know Moo would love to be friends