Let me preface this by saying we've had her thoroughly checked out by the vet on more than one occasion, including very recently, and she's not ill. She's 9. There's also nothing that I can see that would be causing her stress - no house moves, no building, no fights with other cats, not even a small environmental change, no visitors. We are a very quiet household - my DH, my DS who is 8 and very gentle, and me. We have another cat but they've been together since they were kittens and they never fight.
She's always had a tendency to prefer weeing on soft things - my son's bed was always a particular favourite, so we have got used to keeping the door to his bedroom closed. However in the last couple of years she will piss on anything soft - she's now not allowed in the living room unsupervised because she will wee on the sofa, she will also wee on mine and DH's bed, she will wee on my chair in my office. The only places she won't wee are places she sleeps, so the spare bed is always unsullied and so is her own cat bed in the landing, and one armchair that gets the sun.
We've got more litter trays (we now have 5 in total!), we've used the feliway, we've moved the litter trays to different areas, we've done everything I can possibly think of and nothing helps. We have to be vigilant about keeping doors closed and covering up the sofa if we can't be watching her and it's doing my head in tbh.
She does her poos in the litter no bother at all so she clearly knows how to use it, and if there is no other option she will wee in there too - sometimes I can see her sniffing around on a soft thing and I will put her in the litter and she will wee immediately. We've had new things as well so it's not even that she's smelling her wee and repeating the behaviour.
I'm at the point now where the only thing I can think of is putting down a soft blanket or something near her litter trays specifically for her to wee on, as at least that way I'll know where she's done it and I can bung it in the washing machine!
Any ideas????