Forum Discussion
How to change the calendar date format in Microsoft Forms
I had this issue and despite changing browser setting and 365 account languages I tried checking the language on the device.
Under Settings/Time & language/Language & Region is option to change Administrative language settings. Go to the Administrative tab.
Despite having everything else I could find being changed to English (UK) it appears that the "Welcome screen..." and "Language for non-Unicode..." still had entries referring to English (US).
For "Welcome screen..." click on "Copy settings...." and tick both options at the bottom then "OK".
For "Language for non-Unicode..." click on "Change system locale..." and change to English (UK) then "OK".
After restart, I now have dates in MS Forms showing as DD/MM/YYYY.
Hope this works for you too.