As Ruben pointed out, you'll want to run the test script from within your UBB.threads directory if you're on a system with multiple php.ini's or check the two values from within a phpinfo file.
Some hosts will allow you to edit the max post size and max upload size permission within a control panel, others won't allow any adjustments, and some will allow you to override with a .htaccess file.
You'll want to also take care that the "Max file attachment size" or "Max gallery image size" (for a gallery forum) permissions are set for EVERY forum, as this is a forum by forum permission.
