My puppy is not food motivated at all!?

I am trying to train my puppy to sit/come/stay as well as potty training. I try to give her a treat when she pees/poops outside and nothing when she has accidents inside. The problem is she doesn't really care about food. She is totally complacent with dinner (we have tried swtiching to numerous food brands) and she just doesn't really care about treats. I have tried so many different treats, a bit of beef or chicken that I cook, cheese, liver, nothing!!! How can I motivate her and reinforce positive behavior?