Simply turn the adjustment. The fineness of the flour can be adjusted between 'fine' and 'coarse', even during the milling process. The differently sized dots on the scale will help you.
The finest position is somewhat variable: Turn the adjustment knob in the direction 'fine' until the arrow on the adjustment is opposite the smallest point on the scale. Very vivid to see in our video. It is possible to turn a little beyond that, but only so far that you do not hear the stones touching each other during milling (a grinding noise!). If you have turned it too far, the flour flow decreases and can come to a stop. Then if you turn back the flour flow starts again.