Why are some features in my MoodleCloud site disabled?

MoodleCloud is designed with an optimal User Experience in mind, so, in order to make it simpler to use, we have disabled some features and options that may be available in a self-hosted Moodle install.
For configuration settings, if a setting has the label “Defined in config.php” next to it, then it is unable to be changed. It will look similar to this example: