I sympathise Sue , quite often out walking , people actually encourage Reuben to jump up , drieves me crackers ! x
It doesn’t need to drive you crazy; he can learn to discriminate between someone who cues the behaviour and someone that doesn’t.
As always, the question has to be, what is causing the behaviour, and what can you do to get him that same result in a way that is acceptable to you?
Is it purely attention? Is it over excitement? Is it trying to get closer to your face?
If you simply turn your back, then you are trying to punish him for jumping up. But that only works if the consequence you are applying is something that he doesn’t like. If the reason he is jumping up is over arousal, then how does turning your back on him help him to lower his arousal?
So first you need to decide, is this behaviour a conscious decision he is making, or does it come from an emotional place? If it’s conscious decision, then training behaviour is appropriate. But if it is caused by his emotional state, then it’s far more appropriate to address that, instead.
I’ve already said elsewhere that I don’t care if Squidge jumps up after a warning to the person when I’m out, but this evening I wanted to stop and talk to someone without her mugging them. It was someone she knows, so very exciting. I just slowly put individual pieces of food on the floor and she calmed down quickly. As with anything, the more you practice this in easy environments, the easier it will be for you both to use in the real world.
Holding toys is often soothing, so that could work - Luna always brings toys at home and very rarely jumps up inside. The others it wouldn’t work for. So you have to try to find something that works for your dog.