The water softener settings on a Whirlpool ADPF 782 WH dishwasher (yours may be a different number, since I imagine that the controller electronics are generic to a lot of Hotpoint, Indesit and Whirlpool machines) can be adjusted by a key sequence when you first turn the appliance on. The manual instructs that the first thing that you should do after powering-on the appliance is adjust the water softener to optimise the amount of salt that is consumed. Unfortunately a key piece of information is missing about how to know what your current setting is (other than that the factory default is four).
The hardness is displayed as a big-endian binary sequence using three of the display lights on the front of the unit. If you don’t know what that sentence means, look at the image below for an aid to decyphering it.