** I can't seem to find anything called Template Preferences. **
On the administration menu, beneath "Calendar Options" should be "Template Display Preferences".
Whether "Grid Cell Text Size" is an option will depend on the templates being used... and maybe even the script version in use.
** advice to upgrade to 3. 21 - I will add that to my "gotta fix soon list". **
I would suggest you put it on the "
I have to fix this NOW" list.
But its up to you whether you want to leave your server open to the possibility of malicious hacking. If you do decide to put it off, I suggest you at least get a backup made of your site just in case... while you wait.
JMO
Dan O.
www.much2.com