I can’t get him to stop jumping down

My basset knows how to use stairs and although he uses them to climb up he refuses to use them to go down he jumps from high places like my bed and I’m worried it will hurt him especially since he’s still only half a year old. Are there any recommendations on how to get him to stop? I really don’t want him to injure himself and although sometimes I can stop him myself I can’t watch him 24/7. Please give any recommendations for it I appreciate it.