Time setting not sticking

In my style admin I set the time to "Exp. US Format (Monday, April 25, 2000)" but it doen't "stick".

Aslo, I'd like to import some entries from an old guestbook. I know how to do this but Advanced Guestbook seems to use a code(?) maybe international time? for the date & time:

For 11/26/05 15:53 it uses:
1133038393

For 11/26/05 23:11 it uses:
1133047060

Any idea what these number mean or what the conversion formula would be to keep the time & date of my old entries correct?

Thanks.

I found a time conversion Web site. Turns out it's unix time.

http://www.onlineconversion.com/unix_time.htm

It's called a timestamp and is the standard method for storing times and dates. It's the number of seconds fro the 1st january 1970 I believe.