Are you on MS-Windows or a Mac? I’m on MS-Windows and my dates show in the standard numeric format from my MS-Windows settings, big to small, yyyyy-mm-dd.
I also found this old discussion that may help
https://forum.emclient.com/t/how-can-i-configure-the-date-format-of-the-received-column/59158/25?page=2
What I am seeing:
