Hello all, Im new here and would like some help.

I have a 9 year old cat that ive had for about 4 years, after getting her from the RSPCA.

Just recently she has started to scratch the arms of our leather sofas. We have bought her toys, and a scratching post, but she doesn't touch them.
We've tried rubbing pepper into the sofa to try and stop her, but she still does it.
She knows she shouldnt, and never does it when we are in the same room as her, only when we are still in bed.

What can we do to stop her, and protect our sofa please.

Thanks.