Hi Sadose
again I have to mention that I am NOT familiar with your model, so what I have to say is sort of generic washing machine advice.
The function of deciding which compartment in the dispenser gets water at which time is done in two ways, either (1)the cold inlet valve is a multiple valve, and the timer selects which of the inlet solenoids is energised, one solenoid will feed the prewash section, one will feed the main wash section and one will feed the softener section of the dispenser, OR (2) there is only one hot and one cold inlet valve, and the function of directing where the water goes is done by a spring loaded lever connected to the timer, it mechanically turns a nozzle inside the dispenser drawer to send the water flow to each section of the drawer in turn. For this second type you see a thin rod, plastic arm or a cable running across inside the top of the machine from the dispenser to the timer, just behind the dial. The back of the knob has a series of bumps on it (cams) which mover the lever across varying amounts to change where the water nozzle is pointed.
If it is the first type, yout fault may be a leaky cold solenoid or a wiring fault.
If your machine is the second type (which would be my guess) then the linkaage from the timer to the dispenser is out of adjustment. It is a common fault on this type of machine. Usually on top of the dispenser you will see a spring and nearby a pointer, the tip of which fits into a notch. There are maybe a dozen notches in a row, you can adjust the dispenser by turning the pointer to sit into a different notch. Your fault could be caused by - the pointer being in the wrong notch, the rotatable nozzle being stuck or jammed in one position by an accumulation of old detergent or water residue, or possibly even by excessive water pressure.
Have a look and a fiddle, come back for further help if you need it.
Chris.