How to change date/time format?

I can’t find where to change date/time format? I’m in Europe and we don’t use the AM/PM thing, so that makes no sense for us. I need 24-hour format. I’ve been looking around in the menus and I can’t find how to change it, please advice!

You may be interested in this topic

Ahh hmm… Thanks, but I don’t want to add an extension just to handle that, I really think it should be configurable in the application. Just a field where I can write a standard formatting string like “HH:mm:ss”. Maybe one field for date formatting and one for time formatting?