First, how much you are feeding her? She needs to feel a bit hungrier than she does, as this "may" help her want the treats.

Some dogs just aren't food oriented. The praise and petting does it for them.

Boiled chicken breast, string cheese and hot dog are the high value treats I use. Did you know you can cut a hot dog into 77 pieces? No, I can't, but that is what my trainer does. I manage about 60. Small bits! And if you really want to reward something, give 2 or 3; this assumes these actually WORK with your Prue.

If not, then you need to emphasize that YOU are the pack leader; that all good things come from you. She can not get in your lap unless invited; she can not get up on a chair unless invited. These steps help her understand you are the alpha, and she will want to please YOU. We do this all the time with training, but it is more important with the non food oriented puppers.

Finally, she IS still a puppy! A baby, really. Can you do a play time / exercise run or walk before working on training issues? If she is tired, that will help her focus. But at 16 weeks, focus is NOT in her vocabulary yet, lol.

Oh, and just wait until she hits the rebellious teenager stage! He hee, enjoy the fun, don't stress too much, sounds like you are on track.