Dates

Hi again, I feel like for every problem I solve I find 2 more...

This time I'm having problems with the date format. I want it to be m/d/y, but on the join form and such it is y/m/d. In the admin>advanced settings>variables it shows that it should be m.d.Y H:i. So how do I change it sitewide?  What am I missing?

Also the pop-up calendar for the date of birth is different in Opera than any other browser. So strange.