First of all welcome to YorkieTalk. You have come to the right place to get information. If it's yorkie related I can almost guarantee that someone here has "been there done that."
How long have you had your new addition? If he is three years old, it may take a bit of time for him to adjust. Remember when you brought him home his entire world and everything he ever knew changed. Some yorkies don't have issues with change, others take a while to acclimatize to their new surroundings.
My best suggestion would to take everything slow and be very patient with your new little one. Give him some time and space and I would almost guarantee he will come around.
Would love to see pics.