In the “Settings” tab, click the “Edit” button under LANGUAGE / Default (QWERTY) to open a modal to select a different language. You’ll see a warning about keys being reset

This means any keys that you already edited will get reset, and will also reset some keys (including novelties) in the base kits I prepared. This is currently unavoidable :(

For now (until upcoming Yuzu improvements on novelties) the easiest way to get a different language is to start from a keyboard instead of a kit. If starting from a kit, you would either need to edit the alpha keys individually (for dvorak/colemak, this is just swapping which keys are homing) or change the language and then manually edit the keys that got reset.