The introduction of a new cat into the household may cause either the resident or new cat to spray. This behavior usually diminishes over time as the cats adjust to each other. If you find that nothing seems to dissuade your cat from spraying in the house, talk to your veterinarian about the possibility of hormonal therapy. If your cat is squatting Normal elimination behavior involves digging in loose materials, eliminating and then covering the urine or feces. Kittens will instinctively do this without instruction from their mother.
Cats have preferences for the feel of materials they like to dig into.
Most commercial cat litters are made with human concerns in mind, not feline concerns. Try switching litters. Stick to natural clay or sand litters that do not have scents. A cat that is squatting may have developed a preference for a particular surface type or a particular spot. A surface preference may form as an association between scratching on a surface and then eliminating on it.