To secure your wp-config.php from hackers move it one folder above your WordPress installation.
If your WordPress installation is your main site then your WordPress installation is located in your /home/username/public_html folder, simply move it to your /home/username folder
If your WordPress installation is a sub-folder of your main site then your WordPress installation is located in some folder like /home/username/public_html/WPInstalltionr, simply move it to your /home/username/public_html folder