Sounds like the puppy thinks she is the alpha dog and not you. She needs to know that you are leader of the pack. Maybe keep her on a leash (let it drag behind her) whenever she starts to show dominance give it a little tug and tell her "No". After a few times she should get the hint.
Also make sure she is getting enough exercise. Walk both dogs together, and let her know that you are the pack leader. Don't let her walk you......you walk her.
She is still little, she will get it!
Hang in there!