Here is my two cents
and MHO.....
Yorkies are like kids... each one is different and what works for someone else may not work for you....with that said.... this is my opinion....
Sam uses the potty pads and goes outside. This works for me and our lifestyle. He is not confused. He knows when I say potty outside what that means and he will go to the back door to tell me sometimes. I have always carried him; never lead him.
Maybe Kash doesnt know he is supposed to use the potty pads. You may dab some of his pee pee on it so he can smell it and then know this is the place for him to go.
I keep Sam in his crate while I am at work. When we first got started, part of his crate is bedding, part was a potty pad. I cannot imagine not being in a crate, he gets into enough trouble when I am home...
Now that he is older, he has never used it. He holds it till Nana comes home.
Good luck - you sound like you are on the right path with being patient and knowing that it is going to take time.