I had to stop a YouTube video to comment, hopefully some Steemians can relate to my post.
I have lived all my life growing up with cats, and after a while you get used to how they like (and prefer) to live. My best advice to you is to keep a cat's food AND water AT LEAST 6 feet apart from each other. Also, the best place for a little box is the opposite side of where a cat eats and/or drinks. For example you have a living room and kitchen seperated with a wall, so you put food and drink in one area and the potty in the other. They don't need to be miles apart, but being within a few inches from each other is not the best idea. Lastly, (then I will get off of my soapbox:) ) a litterbox should be easily accessable for your cats, if the box's walls are too high and they have to jump into it to do their business, they wont even bother trying. Maybe consider getting a low, close to the floor entrance litterbox for easy access for your cats (if you haven't already).
My advice is not only for those who may be having some problems with their cats but also for those who have cats without any problems...
So thanks for reading(:
I think cats improve our lives so why not do whatever we can to improve theirs! Good suggestions and I agree. :) >^.^<