Hi Eleanor,
MoodleCloud is an off-the-shelf, pre-configured version of Moodle LMS. Any feature/option with "Defined in Config.php" indicates that this has been set and cannot be changed by the user. If you require the flexibility of customising Moodle to suit, you can use Moodle LMS through a Moodle Certified Partner or you can download Moodle for free and host on your own server.
Kind regards,
Barbara