Thank you for reporting this.
It looks like an oversight, and is quite simple to fix. It will be fixed for the next UBBT release.
In the meanwhile, if you are constantly changing the primary administrator account often (???)...
FIND IN
/forums/templates/default/admin/primary.tmpl
(around line 84)
<input type="number" min="2" name="MAIN_ADMIN_ID" size="3" value="{$config['MAIN_ADMIN_ID']}" id="main_admin">REPLACE WITH
<input type="number" min="2" name="MAIN_ADMIN_ID" size="10" value="{$config['MAIN_ADMIN_ID']}" id="main_admin">EDIT: Firefox displays with a smaller text entry box than Chrome. This may have been where field size originally was determined from. Chrome actually reserves the font size spaces in the text entry box for display. Firefox does not respect that, and uses an arbitrary width for character.
