Cindy, welcome to yorkietalk. Rosie is a cutie. The only difference between a yorkie whose ears stand and one whose don't is whether or not the breeder or owner worked on keeping them up. If Rosie has alot of hair on her ears it could be weighing them down. I would have her hair on her ears shaved and if that doesn't make a difference then you can do many things to get them to stand. 7 months old is still young so if you wanted to get them standing you probably could. Alot of people prefer the ears down. It is all about preference.
This site has a lot of good info. Scroll down there is a question about the ears.
http://www.shooterdog.com/alexfaq2.htm#EARS
Keep posting pics we love em.
Camille and Cecilia