Hair does grow in their ears and many breeders suggest you pluck it, do not clip it. There is special powder you can sprinkle in their ear, so you can grasp the hair, and it does not hurt them to pull it out. Joey doesn't even seem to know when I'm doing it. The special powder also helps dry out the ears, ,moist ears can harbor bacteria and lead to infections, be very careful when shampooing as to not get any water in the ear. The white stuff could be from not rinsing thoroughly enough after you shampoo. Joey's breeder said that was the number one reason for white flakey skin, she said that rinse one full minute after you think you've rinsed enough and set a timer so that you know what a minute is like. Also, it's important to use a good cream rinse and conditioner; this also conditions the skin as well as the hair. I'm concerned about her being sensitive about her ears, is there any smell coming from them? There might be some type of infection, and make sure a vet checks this out.
I really like Biogroom shampoo and conditioner, it was specially formulated for Yorkies, and they will send you some free samples if you e-mail the company. They are highly concentrated so mix at least 1 part product to 4 parts water.
Bio-Groom - Exceptional Pet Care Products for Over 30 Years