Hi, D.. Well, it may have been a quick question, but there aren't any quick answers or quick solutions.
First of all, it's got to be confusing to the boy because jumping on the couch was OK when he was a baby, but then you suddenly changed the rules. You changed the rules 2 years ago, but he's probably trying to figure out why. The more confused a child is, the more he will act out in order to try to figure out why something is the way it is. They keep causing the situation to see how it turns out. Is the rule being enforced consistently? Every single time? or is there someone who lets him jump on the couch sometimes? If that's true, then your son has no way of knowing when it's OK and when it's not.
#2 -- jumping on the couch is fun!! He seems to like it a whole lot. Did he have a bounce chair when he was a baby? Maybe he likes the feeling and wants to feel it again. Remember, a 4-year-old has a very short attention span and very little impulse control. If you want to re-train him not to jump on the couch, it's going to take time and patience to get him motivated to control that very fun impulse.
Now, is the problem that when he's on the couch, he uses it for a trampoline? Maybe you can give him an alternative to that. Most kids love to be bounced in the air or thrown up and caught. He's probably too heavy for this now, but maybe you can get one of those mini exercise trampolines and help him bounce on it, you know, catching him and making sure he doesn't break anything. That leads to #3 --
#3 -- kids will substitute negative attention for positive attention if they feel they aren't getting enough. Make sure he's not feeling ignored.
#4 -- make a game out of sitting on the couch properly. Show him how you want him to get onto the couch (just sit down, not a running leap or a vault), and time him to see howw long he can sit there without bouncing or trampoline-ing. And don't necessarily expect him to sit still for a very long time. If everyone is sitting on the couch watching TV, have everyone get up during the commercials, stretch, bounce around, etc. Remember, he doesn't have the attention span you have, and he probably doesn't have your fatigue at the end of the day, either.
Make sure he's got enough physical activities during the day to satisfy his need for moment and to expend energy. Kids who don't get enough exercise get antsy and will sort of explode at odd times. Also remember that he may be more active than other children you have known, and so his needs may be different from theirs and from your needs and behaviors when you were a child.
He sounds like a delightful, bouncy, energetic little boy. I hope you can find a way for everyone to be happy on and around the couch.
Peace,
Syl