I forgot AGAIN!!!

I've been meaning to buy batteries for the remote control but everytime I go to Walmart I forget. Tonight I had to switch some around from different things hoping that the right combination might make the tv remote work!!! LOL I've been to walmart at least 3 times since they went out in the remote. Everytime I'm there I walk around feeling like I'm forgetting something but can't figure out what!!! I also need to pick up some air filters but I can never remember what size!