Clean the couch thoroughly first to remove any urine scent do not use anything with ammonia in it. Use lemon juice it takes the scent out and cats hate it.
They sell a product really cheap at the pet store that stops cats from scratching your furniture. Spray this on your couch and the cat won't pee on it.
The cat urinating inside the house shows that it feels insecured.Keep a shallow plate filled with soil in a corner of your room.Your Problem will be solved.
