My oldest cat, Ramona, has a history of peeing in inappropriate places, usually in the corners of the room. About a year or so ago, I had all the carpet removed in my entire house, and replaced with wood flooring. She still pees outside the box, but only very rarely. The vet checked her out physically, said nothing was wrong. He prescribed an anti-anxiety medicine, but I could never get her to take it. Maybe your kitty smells other cats that used to live in the apartment? Good luck with her, she sounds sweet. I'd definitely get rid of the smell couch, I think it just encourages her to keep peeing on it!