Simple ways to increase ventilation/air movement in the house?

Hello!

I live in a prefab/mobile home. We use a window AC in the living room which helps the whole place and have our tinier old one in the bedroom for the night when it gets too hot (we are really sensitive to heat and live in Colorado lol).

The thing is, from the moment you step away from the general blast area of the AC it gets hotter again, and just the air circulation around the house is not great as a whole. Even with the ceiling fan it didn't seem to help much. I tried cracking the other window in the living room which is directly across the AC, and the kitchen one (open kitchen but I put a curtain to separate from the livingroom), but the kitchen one is in a corner and really tiny, so doesn't seems to help much neither.

I seems to vaguely remember my grandma used to have some sort of tiny fans, not hooked to anything, in the windows in her bathroom back in Europe, but I have no idea how it's called and I'm affraid it would affect the temperature too much in winter. Colorado gets very hot in summer and very cold in winter, so it sucks too to imagine some solutions that wouldn't create too much waste on AC/heat.

Do you folks have any successful tips, DIYs or worth buys to help with that issue?

We're thinking of maybe getting an air purifier for the "stuffy" effect which doesn't get away even with regular window openings, but it wouldn't help to convey the AC air.