Because he’s so young, I assume he’s not neutered yet? A lot of unneutered buns pee and poo outside their cages in order to mark territory. Some have fine litter habits, but some just can’t help the hormones that tell them to mark everywhere! Haha. I think neutering should help a lot.
Also, couches are a very popular place for buns to pee because it smells so much like humans that they want to claim it as their own. I would block off the couches for now because it might not be possible to stop him from marking there. If you kept him off the couch, do you think he would still pee all over?
ETA: Have you tried adding more litter boxes to your living room? (maybe even one on the couch) I would add some more, put some hay in them, and if he uses them (or even hops into them) praise him and give him a treat. He might figure out that the litter box applies even when he’s out of his cage.