What I found that works great for my cats not scratching up on the furniture is using a scratching post that has a large base. The problem with some of the scratching posts that are bought in stores like Wal-Mart or the cheap ones that you find at Petsmart are not sturdy enough for a strong cat to use. Once they tip over, the cats avoid them like the plague.

Try spraying catnip on the newly purchased one to entice the cat to use it. I also recommend using SCAT which sprays air and it uses a sensor so when the cat passes by it, it sprays a puff of air at the cat which deters them from going near the surface. It works great on mine. I don't recommend declawing an older cat since they tend to get infections in the paws that could become potential problems later in life. Try the large base scratching post first before reverting to declawing.

I'll try to keep in touch. It's been pretty hectic lately for me. Thanks for the response. XD