I am currently training a siberian for therapy dog certification, to go into hospitals and such. Seeing one problem though, when we are out in public or new people come to our home he jumps up on them to give kisses. I taught him to UP on command but now he does it on his own all the time. No one is afraid of him and he is very gentle. How do I correct this without making him wary of not UPing when I ask him to? I like the fact that he wants to give kisses and is curious but I dont want him to jump on people without being told to.

What would happen if your dog would jump up to give a "kiss" to a feeble / elderly person / young child and the dog knocked them over and they get hurt?

You taught the dog to "UP" on command, evidently when he started to "UP" on his own, you didn't correct him. I would give him a stern NO at the same time a sharp correction with collar/leash.

Let him know it's OK to "UP" only on command, other than that, it's time to stay on all fours.

My personal opinion

First teach him to sit to greet all new people. At the same time correct for jumping up every single time using a prong collar and line.

I would first go about retraining the sit with food holding it just inches from his nose and making sure he keeps his booty on the zee floor,where the dog start to realize that the tighter he locks up in the sit ,then he gets fed.WHEN YOU get in the dogs mind i meet people i jump then i get pain the dog start to realize that the people he is meeting generate the pain, this in the dogs mind creat confusion and anxiety ,which leads to faster and stronger jumping up ,and then trying to get back without getting prong correction .The key is to give the dog a option to jumping up. This option is obedience ,keep your butt on the floor or ground or i will rip your head off , not if you jump up on people i will rip your head off . How in the dogs mind can he be gentle with people when every time he meets them ,you yank him so hard it triggers adrenaline spike from the pain of prong yank ? Take your time and break the issue into very small increments that the hund will savy and then give yourself some time to get there. remember with dogs if your trying to get a foot with them ,sometime if you get just a fraction of this it is good so long as there is progress . GOD BLESS

good advice. I will work on having him sit to greet people. I need him to up on command to put his paws up on a tall hospital bed or chair so patients can see him.