Cannot change database from configure.php in osCommerce

Question

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I tried both includes/configure.php, and admin/includes/configure.php, neither contains data about the real database. these are the data in the admin/includes/configure.php:

defined('DB_SERVER_USERNAME') or define('DB_SERVER_USERNAME', 'root');
defined('DB_SERVER_PASSWORD') or define('DB_SERVER_PASSWORD', '');
defined('DB_DATABASE') or define('DB_DATABASE', 'trueloaded');

and this is in the includes/configure.php:

defined('DB_SERVER') or define('DB_SERVER', 'localhost');
defined('DB_SERVER_USERNAME') or define('DB_SERVER_USERNAME', 'root');
defined('DB_SERVER_PASSWORD') or define('DB_SERVER_PASSWORD', '12345678');
defined('DB_DATABASE') or define('DB_DATABASE', 'trueloadeduk');

nothing happens if I change the database here.

I am using the latest version of oscommerce 4.13 ​