When puppies are nursing, they learn from their mothers to relieve themselves outside of where they eat and sleep. Your adult Yorkie may have forgotten what her mother taught her, but with repetition and a lot of positive reinforcement, your Yorkie will catch on .
Take your Yorkie out every morning to the same spot to relieve herself. This familiar spot will make the housebreaking process less stressful for her, and the repetition of the same time and place each day will help her learn.
Reward your Yorkie with affection and a treat every time she relieves herself outside. Don't give her commands or rush her to do her business. Stay calm if she makes a mistake and relieves herself inside. Just take her out to her designated potty training spot and let her finish there.
Keep your Yorkie on a consistent housebreaking schedule. Take her out when you wake up in the morning and before going to bed at night as well as every two to three hours throughout the day. Stick to the same daily schedule as best you can until your Yorkie is no longer making mistakes inside the house.