Sorry for necroing the thread, but I am new to Unraid, and stumbled across this issue today. After spending several hours on this, I was able to come up with a solution for my use case that may lead others on the right path. Editing docker container variables was the only thing that worked for me (editing kdeglobals, bashrc, locale.conf and messing with locale-gen were dead ends). Here is what I did to make it work for me (as a user based in the US):
1. Edit the docker container.
2. Click on "Add another Path, Port, Variable, Label or Device"
3. Edit Configuration should look like this:
Config Type: Variable
Name: Variable:LC_TIME
Key:LC_TIME
Value: en_US.UTF-8
The above settings will show dates in MM-DD-YY AM/PM format in the "modified" file listing. FWIW, I tried en_DK.UTF-8 as an LC_TIME variable (which is supposed to list files in YYYY-MM-DD format), but files were incorrectly displayed in DD-MM-YYYY format on my end. Not sure if you or others outside the US will have the same result, but it might be worth a try.