UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? Date Format - possible to change across the board?

I created accounts for all 200 or so of our employees under the assumption that what I'd selected as the default date/time format (under UBB display settings) would also be the default for each user when logged in. I just found out that every one of them has it all set up differently (European style, with the day first) - do I really have to edit every single person's settings, or have every single person do it themselves? Is there any way to change all users' settings to the same date format by default?

Thanks for your help.