Website language vs typing language
The interface language changes menus and labels. It is separate from the language you type lessons in. To change what you practice, see the difference between website and typing language.
Change the theme
Follow the steps below. Each one matches the highlighted area in the screenshot.
Dark mode and accessibility
Dark mode is easier on the eyes in low light and is fully supported, including right-to-left layouts. You can revisit these and other preferences any time from your profile settings.