The left scale is Reading first (tilt left) or Meaning first (tilt right). This is especially useful if you have 1x1 mode enabled, which pairs the Reading and Meaning questions back to back.
You probably only need to tip the left scale if you use 1x1 mode, though maybe some people find it useful without 1x1.
The right scale is Level first (tilt left) or Type first (tilt right). You definitely need to tilt this one, otherwise it ignores your settings in the middle, and your items will still be in random order.
If you tilt the right scale to the right (Type first), with the settings you described (7>6 & rad>kan>voc) you’ll get: Rad7, rad6, kan7, kan6, voc7, voc6
If you tilt the right scale to the left (Level first), you’ll get: rad7, kan7, voc7, rad6, kan6, voc6