The DGA head does not get adjusted. It gets set (IIRC) at the lowest setting and the knob removed. The DGA head is fastened to the chassis , not allowing for movement. This setting works for all formats from 35mm through 2-1/4x3-1/4. The knob can be replaced if you want to revert back to a condenser head.

To change format, merely change lens, 50mm for 135, 80mm for 6x6, 105mm for 6x9, or whatever lens you use for a format.