Lower dentures are more difficult to keep in because of the tongue, cheeks and lips. Also the bone in the lower jaw shrinks more than in the upper jaw and therefore there is less ridge height and width to retain the denture.
If you don’t have any lower teeth then you could try a lower denture. They work for some people but at the end of the day it is piece of plastic resting on a slippery surface that is trying ti stay stable!
Kind regards