In pet stores (Actually last weekend I saw it in Petsmart)
They have a whole variety of sprays, some are to relax your cats in stressing times and some are to stay off
an area such as your sofa.
The only thing you have to check is the age. Example: For cats (number) of weeks and up or ask a person there.
There's also the water squirt bottle to scare them away whenever you catch them on their way to mischief.
There's feliway (another spray) that will keep them off your couch.
Make sure to have more than one scratching post. If you have one in a bedroom or any room make sure to have another one in the living room or where your couch is. 2, 3, etc it all depends on how big your place is.
Hope this helps