Bearscs54

I adopted Zola from petco in June. She is a great dog wonderful with kids and other dogs. The only problem with her is she is seems to be scared of me. I never yell at her or hit her. She will go out and play with kids and wife but if I try to play with her she will just cower down and won't move. Sometimes if I make a sudden movement she will cower and pee. I was just wondering if there's a way I can help her build her confidence back up. I don't want her to be scared of me. I'd like to be able to play ball with her outside and run around with her. Any advice would be appreciated.