where are you changing the settings? in webdate admin?
you may need to access the forum setting directly through phpBB2
go to
http://lezgirlz.net/phpBB2log in as the admin.. I believe is binky@@@@
you should see a link to administrator control panel at the bottom of the forum here you should be able to update the settings..
if this does not work let me know and email me the admin so I can have a look
Paul