Picking the right keyboard layout is the one setting worth getting right before you start, because every lesson afterwards depends on it. The course teaches keys by position rather than by letter, so switching layout rebuilds the whole curriculum, the hand guide and the finger prompts around the keyboard actually in front of you.
QWERTY is the default and covers most English-speaking countries. QWERTZ is the German and Central European arrangement, with Y and Z swapped. AZERTY is the French layout, where the home row little fingers land on Q and M rather than A and semicolon. Dvorak rearranges the letters entirely to put the common vowels under the left hand, and has its own practice guide.
Layout is not the same thing as language. Changing the layout changes the physical keyboard and the finger map. Changing the lesson language changes the practice vocabulary, and picks that country's layout with it.
There is a high-contrast theme, a dark theme, a reduced-motion option and a dyslexia-friendly typeface. Spoken finger guidance reads each prompt aloud, which is aimed at younger children who cannot yet read "left pinky". Strict mode makes a mistyped key block until it is corrected; it is off by default, because being trapped on a key is the fastest way to give up. Everything is saved in your own browser.