[Typo3] Start - Stop Date, how do I change it?

[Marlies C]

When I want to set a start and stop date for my page content the date always 
shows in the European format: day month year. The same goes for the date for 
the Header in the record content section.

Where do I change that without too much trouble. It is extremely confusing 
for North American users.

Thanks

Marlies
www.mcuniverse.com