I change their food now and then. If they have any stomach distress, I will boil lean hamburger and potatoes (you usually use white rice, but I don't feed mine grains). or, you can add ground flax to their food, to help solidify stool. I have never fed my maltese grains. My first maltese had stomach issues with grains, so I eliminated them years back.
Mine do eat kibbles and never have had an issue with it; ever since they were puppies. Even a Yorkie puppy that was under a pound when she came to me, ate kibbles.