Hi! Welcome to YorkieTalk!
I will let others answer about the potty pads. Mine are trained to go outside so we never used pads, but we did crate train (but I wouldn't recommend putting him in a crate all day without breaks). Anyway, he's not going to be trained at 14 weeks. Usually Yorkies don't start to get it until they are more like 16-20 weeks old and they aren't fully trained (no accidents) until they are between 6 and 18 months old.
It's not for lack of trying or lack of intelligence, but they just have tiny bladders and if you want to avoid accidents you have to let them out like every hour. If they need to go, their little bladders don't give their brains much notice! If you are going to train outside it helps to teach him to use a bell. If you want him to go outside then you probably shouldn't use the pads, but you also can't expect him to hold it all day so you might need to use an ex-pen for a while with his bed, toys and a pad. Just relax for now and realize that if he isn't getting it yet it's not because you are doing anything wrong. If you are consistent he will know just what to do once his body gives him a little warning. It also helps to give him a treat when he does the right thing but you have to be watching him to do that. I don't know if you should stake out the pee pad, but you do have to catch him doing it to reward him! if you go outside take him on a leash and take a treat with you!