It's not on. Because your host is using PHP-CGI. SMF doesn't like php-cgi and is disabling "Search engine friendly URLs" from your admin area.
SMF is checking if you have ini_get('cgi.fix_pathinfo') ==1 and if is not then you cannot run Seo4SMF or "Search engine friendly URLs"
To workaround this problem just look in QueryString.php after this line
if (!empty($modSettings['queryless_urls']) && (!$context['server']['is_cgi'] || @ini_get('cgi.fix_pathinfo') == 1) && $context['server']['is_apache'])
and replace with
if (!empty($modSettings['queryless_urls']) && ($context['server']['is_cgi'] || @ini_get('cgi.fix_pathinfo') == 1) && $context['server']['is_apache'])
Test and see if is working ... just remember to backup your files before any modification.
Regards
That didn't work for me, my hosting is very very dramatic with htaccess files i get blank page if I replace the line.