If you could make your pet understand one thing, what would it be?

If I could make my pet understand, one thing, it would be to go to the bathroom and use the toilet so that there would be no mass to clean up and it would be a easier relief for me too. Have to clean up behind the dog. That is such a relief, when you don’t have to go to the bathroom outside all the time to help the dog, go to the bathroom specially, when you have bad knees, that would be a great help to teach the dogs to go to bathroom on the toilet.