suPHP Detailed info
/usr/local/etc/suphp.conf (Detailed suPHP configuration)
/usr/local/apache/conf.d/suphp.conf (suPHP configuration for Apache)
There is also suphp configuration in the vhost files for each vhost.
If you don't want to allow users to modify and use custom php.ini per folder you can do that by placing an empty php.ini file into users home folder. The empty file will use default server php.ini and will not allow users to load any custom changes and other php.ini files.
Now secure it so users can't change/disable it
chown root.root /home/USERNAME/php.ini chmod 555 /home/USERNAME/php.ini
Note that each version of PHP in PHP selector has a different php.ini file.
You can edit php.ini files for each version from the php selector in cwp.admin