A pop-up list offers a choice of 3 doc-wide default formats for the values of Date-type attributes shown in a note's Key Attributes table.
The default is to show the local OS' short date format, then a comma, and then the hours:minutes.
This choice can be overridden at document or note level by setting a date format string in $KeyAttributeDateFormat. The attribute's doc-level default is "" so as normally to inherit the format set in the above pop-up.