Thanks for the advice! He has 3 different boxes, meanwhile my senior cat only uses one other box which he will use too. His preferences are interesting. There's one box he will NEVER poop in, only pee. That's where he used to leave the puddles.

Your cat is so cute! He looks like a lion sitting there. And so fluffy that it sticks out between his toes! Aww
Hopefully he will get into the habit.