Click the "Switch to PHP Options" link:
A list of the most common PHP variables are listed, click the option you wish to change and select or change the value. Click the Apply button and the Save button at the bottom to apply the changes:
Other PHP variables can be manually changed via a .htaccess file in the public_html directory of an account.
A full list of the PHP variables can be found here: http://php.net/manual/en/ini.list.php
The following is an example of PHP variables being modified via a .htaccess file:
php_value memory_limit 256M
php_value post_max_size 128M
php_value upload_max_filesize 128M
