i trained lily to go on a grass patch inside since she likes soft CARPET material to go on lol. when we first got her she would go everywhere in the house until i got a grass patch from petsmart and every time she went on the carpet i would say no in a stern voice and put her on the grass and say "go potty" eventually (about 2 weeks) she learned to use that instead of carpet. now i can say "go potty" and she instantly uses the bathroom on her designated grass spot. hope this helps. yes its kind of gross to clean the grass but i think its worth it
especially since we live in an apartment.