As of PHP 5.3 you can use .user.ini as an configuration file per User.
Best wishes,Fabian
Why in wp-content? Try creating a php.ini in /var/www/vhosts/domain.com/httpdocs.
Also, did you edit wp-settings.php? This is the default:
if ( !defined('WP_MEMORY_LIMIT') ) define('WP_MEMORY_LIMIT', '32M');