advanced guestbook server time error

I am in the admin section of the 2.3.1 guetbook and I am unable to change the server time on my guestboolk. Everytime I change it, it defaults to a new setting.

Server Time Zone Offset
You can offset the time drawn from your web server. For instance, if your server time is EST (US), but you want all time to reflect Pacific Time (US), you would have to offset your server time by placing the time zone difference in this field (for this example, that would be -3. You would place -3 in this field). The default is for there to be no server time zone offset (0).

It stays here no matter what 12307
I have tried to change it to zero, etc. this was a problem with the old guestbook. I just assumed upgrading to the new one would fix my problem.....

HELP