Well make sure the area where they have made their mistakes is cleaned very well, either with dilute bleach and dried or with vinegar/water(but not both).
Secondly, we only say no to Chibi when he goes in the wrong spot, but we don`t raise our voices, since we were told/and read several times in different books that it makes dogs nervous and doesn`t really help. We give him treats (really small pieces of lunch meat or tiny treats we buy at the pet store) and lots of praise (while he is going) when we catch him going in the right spot.
But the trick is to catch them going in the right spot and praise, praise, praise! It has worked for us, hopefully it will for you too!
Also maybe you could hold her in your arms when on the couch, it seems that dogs will not go on their mommy`s and daddy`s. But if she suddenly squirms then she probably has to go!
Good luck!
