Default date format of DD-MMM-YYYY

Summary

Make date format DD-MMM-YYYY for all users

Content

Hi -

We are trying to make the date entry consistent across all users by changing the date format to DD-MMM-YYYY at the site level.  What we have been noticing is that the date format gets changed for existing users but when we add a new hire / user takes into account the user settings which default it to a different format.

Is there a way to change this so that it will also apply for any new hires after the changing the setting?

Thanks,

Roy