By default, the date format shown on the online platform and to app users in the American format, "MM-dd-yyyy." This can be changed by editing the contents of the "Date Format" region within Apps > App Setup.
Simply enter the preferred date format in the highlighted area above (e.g., yyyy-MM-dd), and then click "Save" in the upper-right corner of the page.
Note that in this page, time format can also be changed in the "Time Format" field right below "Date Format."