Re: Date picker format in Forms
HI @Anonymous
I think the calendar picker picks up the browser settings and not the O365..
But O365 mingles a little bit the configurations. My instance shows up content in English and Portuguese and PT and US regional settings. Honestly it's tricky. For example here's my calendar in a form:

Control is tricky but could you please try to check if, changing your regional settings in your browser / OS, it changes?
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Cheers
Manuel