Although most cats prefer clumping litter some prefer another type. Record which the cat uses. Add more litter pans. Many cats also prefer to use one pan for urination and another for defecation. The pan preferably should not be a covered box because the cover traps the odor.
Most cats prefer a large open pan with low sides.
If tracking litter is a problem, put the whole box in a larger cardboard box. The pans should be located in a quiet place. The pan should not be under anything that would hinder her movement nor should it be too close to a radiator. Offer a variety of pans - plastic, metal, cardboard, square, round, covered, open or tray so the cat needn't jump in. Some cats will use a very large pan such as that sold at hardware stores for mixing cement.