How to prevent cats from destroying furniture?

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We have two cats. I trim their nails at least once a month (and I wouldn’t declaw, I think that’s cruel- they literally take off part of their toes) but constantly they try to claw up one of our couches in particular, as well as the wooden banister by the staircase. They have plenty of toys, a scratching post (which they use) and never seem bored. They’re always playing, cuddling, chasing something, or looking out the windows, and always seem very happy. So I think in their minds they probably see it as another scratching post for them.

How can I break them from this habit or prevent them from damaging things? We’re looking to buy a house soon as well as need to get new couches if we move and I don’t want them to destroy anything. Any tips?