Some how it is hard coded to mm/dd/yy in both Add to library and copy & import
How to change it?
On an iMac I am using
new build based on https://github.com/darktable-org/darktable/commits/darktable-3.4.x (osx >= 10.15)
includes liquify & waveform histogram bugfix
plus
darktable-3.4.0+61~g9e9498259.dmg
(handle with care - backup your stuff first) for productive stuff prefer official dt 3.4 build
If you mean renaming files when importing from a camera (if not, please be more specific and upload a screenshot):
You define the base folder for storing imported images and the naming pattern of subfolders and individual images in the preferences dialog (see Section 8.2.2, “session options”).
And darktable 4.0 user manual - import
The base folder for storing imported images and the naming pattern of subfolders and individual images can be set in preferences > import.
I’d assume that comes from your operating system. For example, on Windows (darktable 3.4.1.1) I see:
@Rajkhand - it looks from the screenshot like you’re using 3.5.0+2525 build instead of 3.4.0+61…
the date format is dependent on your locale. If you set different language in darktable (eg via forcing english language) then it might default to C date, which uses americanized way of formating date (so literally the worst date format ever with month first).
Google <your OS name> date format or change locale.
it is in this dialogue only this problem is there
TBH this might be a problem with how locale is set in darktable, because I have pl_PL locale, but force english language and I experience the problem on linux.
Honestly - americans COULD use some decent date format and we’d have no problem… or we could instead force ISO date format (eg 2021-06-17) for import window 
i have changed my locale to this
LANG=“en_GB.UTF-8”
LC_COLLATE=“en_GB.UTF-8”
LC_CTYPE=“en_GB.UTF-8”
LC_MESSAGES=“en_GB.UTF-8”
LC_MONETARY=“en_GB.UTF-8”
LC_NUMERIC=“en_GB.UTF-8”
LC_TIME=“en_GB.UTF-8”
LC_ALL=
still it displays in mm/dd/yy 
i don’t have an idea how darktable deals with localisation for the new (3.5) import file dialog since i didn’t check the source.
At least it’s not consistent to other import dialog (e.g. importing styles or xmp)
So maybe it’s worth to file an issue…
What about if you set LC_ALL as well before starting darktable?
i compared my windows and osx build - the windows build doesnt use german date format if set to german language - on my osx machine everything is fine.
Please try opencl: ensure environment locale is restored after init by kmilos · Pull Request #9261 · darktable-org/darktable · GitHub if you get a chance
@kmilos
I do not know how to set LC_ALL , can you guide me? Also thanks for raising the issue hope someone does something about it.
I use ubuntu 20.04 and dt 3.5.0~git2558.1fc2d0e223-1 and I don’t have this problem.
My locale configuration is:
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE=“en_US.UTF-8”
LC_NUMERIC=it_IT.UTF-8
LC_TIME=it_IT.UTF-8
LC_COLLATE=“en_US.UTF-8”
LC_MONETARY=it_IT.UTF-8
LC_MESSAGES=“en_US.UTF-8”
LC_PAPER=it_IT.UTF-8
LC_NAME=it_IT.UTF-8
LC_ADDRESS=it_IT.UTF-8
LC_TELEPHONE=it_IT.UTF-8
LC_MEASUREMENT=it_IT.UTF-8
LC_IDENTIFICATION=it_IT.UTF-8
LC_ALL=
Lang English but Formats in Italian (my principal language) to avoid your problem.
If I set LC_TIME=en_US.UTF-8 DT show dates in mm/dd/yyyy format
With LC_TIME=en_GB.UTF-8:
my setting is
LC_TIME=“en_GB.UTF-8”
but still it shows the date in mm/dd/yy format
i am using a Mac with OS X Big Sur 11.4
i don’t know… but I read that comment in DT code darktable/osx.mm at e8cb2cb1d9a2b34a4bbe27278247dae0ff09c3c8 · darktable-org/darktable · GitHub
I don’t know if it can help.
I know you were joking, but I wouldn’t be opposed. Here in Canada, we are constantly exposed to both mm/dd/yy and dd/mm/yy dates. The sanity of ISO 8601 dates would be most welcome.
I’m NOT joking. If whole world used single stable date format that’s easy to parse for both humans and machines, we’d have soooo much less to worry about when handling date inputs/display/outputs 
