Rewards work! If they get a treat every time they do their business outside, it doesn't take long for them to realize that they get nothing for accidents in the house. One thing I read over and over is never scold them for accidents in the house. Just be consistent with taking them out often. Crate training is good also, they will not mess where they sleep.
I eventually took the carpet out of my downstairs because they seem to be attracted to carpet. We did keep carpet in the bedroom and my older girl has never made an accident in there because that is her bedroom as well. We keep the little one in her crate at night. Since taking the carpet out is not an option in an apartment, I would make sure to get a good spot cleaner with enzymes made for dog accidents. Hopefully that will take away the smell and they will not be tempted to go there again.
Good Luck!
__________________ Kim  Mommy to my angels, Chelsey, Zoey, and Cooper |