Tap a string or swipe across them all.
A7: index finger on the G string, 2nd fret, middle finger on the D string, 2nd fret, little finger on the A string, 4th fret, ring finger on the E string, 3rd fret
Songs with A7: Der Kuckuck und der Esel, Weißt du, wie viel Sternlein stehen