leaving the AC on

Yes hello, I am an HOU (and air conditioning) noob. Apparently you keep your AC on or your house will get moldy? I see most people keep it in the mid-70s, from what I’ve read here.

I have one in the living room window and one in my bedroom window. The one in the living room is only on setting #1 out of 10, and I change the bedroom one anywhere from #1 when I leave the house to #4 when I’m trying to sleep. Surely they should be turned off at some point? My electric bill was $15~ when I moved here in March and I just paid $35~ for May. I haven’t had an electric bill before, so nothing from the past to compare this to. You really just run it 24/7??