Changing the date format

I have read this support request But I don’t understand the answer.

The date displays correctly in the Dashboard view of all Events but does not display correctly on an Event editing page or on the front end. I would like U.S. (M/D/Y) formatting, not European (D/M/Y).

Is the response below saying I have to modify the plugin code or my theme code?

Plugin Supportangelo_nwl (@angelo_nwl)
3 years ago
for events > settings > formatting > date/time > date format you need the format from this page – https://ww.wp.xz.cn/support/article/formatting-date-and-time/

for date picker format, you can try this http://docs.jquery.com/UI/Datepicker/formatDate`

The page I need help with: [log in to see the link]