Defaults

The theme, language, time zone and date format for users who chose none

Defaults sets how the app looks for a user who has not made a choice of their own in their preferences; a user’s own choice always wins:

Field	Choices	Without a choice
Default theme	Light, Dark or Color, with one of 12 colours for Color	Light
Default language	The languages of the app, kept in DEFAULT_LANGUAGE	English
Default forms view	Tiles or List, for the forms page	Tiles
Default time zone	UTC, each user’s browser, or any zone by name	UTC
Default date format	YYYY-MM-DD, DD/MM/YYYY, MM/DD/YYYY or DD.MM.YYYY, shown with today’s date	YYYY-MM-DD

The language is an environment variable and applies without a restart. With ALLOW_ENV_EDIT set to 0 the page shows it read-only.