my phpbb3 forum showing this msg Your config file (config.php) is currently world-writable. We strongly encourage you to change the permissions to 640 or at least to 644 (for example: chmod 640 config.php).
It just means you need to chmod your config.php file to either 640 or 644 (640 recommended) you can do this in your FTP or your web based file manager in your cPanel.