How do I establish dominance over my rabbit?

My 14 week old female Californian rabbit had recently began to hump my arms to establish dominance. I would like for this to stop, are there in other options besides spaying her? I've tried scolding her and holding her down over her shoulders with my palm but this never seems to work, why doesn't it? Also, how do I get her from peeing on the couch? My mom hates it....

She should outgrow it reasonably soon. You could try to put the rabbit on the floor, and GENTLY hold her in place. Don't allow her to get up and move, but don't FORCE HER DOWN, just make sure that she can't get up and go anywhere. That should show that you are the dominant species.