Open social date format
Ensure you have the Field UI module enabled.

If you go to Structure &gt; Content Types &gt; Event &gt; Manage form display (admin/structure/types/manage/event/form-display) then you can change the form widget that is used there.

The Date and time widget which is the default has no configuration available. However, you can also use the select list widget which allows you to specify Date part order and Time type.