I can't offer much in the training department itself. I have only been successful by being there to take them out every 2 hours til they got the idea.
But .... Another angle to look at is the quantity and consistency of poop. That is probably making this all the more frustrating. I know if I had to come home to poop smeared on walls, gate, floor and dog, I might not be as patient as needed for house training. So, what are you feeding your puppy? I find with the high quality dog foods, you will get much smaller, compact, less frequent poops that are more on the solid side. They should be nice and easy to pick up. If he is smearing poop everywhere, it sounds like the stools are much too loose and maybe too much of it.
Some foods even advertise -- low residue. If you feed junk dog food, you will get big ol' messy poop. I feed Canidae and if they do have an accident, it is just a minor thing to reach with a tissue and pick it up. Go to this site and make sure you are using a 5 or 6 star food:
Dog Food Reviews - Main Index - Powered by ReviewPost
If you are already feeding one of these high quality foods, I would ask the vet about so many loose stools. If nothing else, maybe someone else will benefit from the link. Good luck with what is the most frustrating aspect of Yorkie ownership -- but it's all worth it!