Work with her. I "rescued", purchased a really well bred female GSD when she was almost 3. She was out of the same male as my male GSD and was a super sweety. She had been treated not very nice in both training and life. It took a while to become a team, but she got her BH with comment about being one of the few happy dogs there. Didn't pursue her titles, as she was happy to love on everyone one until obedience was added to the mix. We were a super tracking team. I just tried to figure out new words to use for things I thought she had be taught before coming to me. And when you use shaping in marker based training, all you do is up your criteria before marking and giving the reward. Go slowly and be fair and she will understand.
dogbyte Cathy, Rossi ( the Dutch shepherd) and Gunny (the Czech/DDR GSD) with Zoey, Chance,Xara,Gracie, and Jaden snuggled deep within my heart