Why should I not use GSettings overrides?
GSettings overrides are used by distributions to adjust default settings for the GNOME desktop and apps. dconf overrides were designed for system administrators to adjust default settings and set mandatory settings for the GNOME desktop and apps.
What are vendor overrides?
Default values are defined in the schemas that are installed by an application. Sometimes, it is necessary for a vendor or distributor to adjust these defaults.
Since patching the XML source for the schema is inconvenient and error-prone, glib-compile-schemas reads so-called vendor override files. These are keyfiles in the same directory as the XML schema sources, which can override default values.