Best recommendation is to take her to the vet and make sure this isn't some kind of urinary tract infection, that can sometimes cause them to stop using the box.

Are all of the cats spayed/neutered?
Is the cat alot older like over 10 years?

At home, make sure to clean the areas she's using with a product designed specifically to eliminate pet urine odors, not Fabreeze (although it's a safe product I can tell you from experience it doesn't totally eliminate the urine odor). Cats sense of smell is way better than ours and if she smells any odor there she might continue to think it's her potty.

Add more litter boxes. Rule of thumb is 'one box per cat plus one extra'. Some cats are really fussy about sharing a litter box. Make sure to scoop out the boxes every day.

Do not use any cleansers when you wash out the boxes, only use HOT water. Cats sometimes don't like chemical smells, or pretty smells that we humans tend to like.

You've tried outright switching litter, have you tried just having a different litter in each box so she has a choice? Make sure at least one is totally unscented.

Beyond that try a product called Feliway, it's a cat hormone spray that makes them think they've marked the area alread and then they won't urinate there anymore.

But first thing should be to see the vet to make sure this is not a medical problem.