The manual mode is only interesting if CCIP is not available (e.g. due to damage).
In manual mode the crosshair is fixed and are not calculated. This corresponds to the Reversionary sights as used for example in World War II (see Bf 109). The pilot then has to aim himself and take into account the variable parameters such as speed, angle of attack, altitude etc. This requires extensive experience and practice.
With the UFC you can adjust the vertical position of the crosshair in mils from 0 to 270.
Here is the description of the necessary steps:
In the HUD the crosshairs move depending on the Mils value set and the value is also displayed on the right.