Mosfet 50wx4 indicates a feature of the Pioneer car radio. It isn't a model number. One Pioneer car radio/CD player with this feature is the DEH-1500. On this model, you need to turn off the unit to set the clock. Press and hold the Source button (to the left of the preset tuning buttons) until the device turns off. Press Audio (upper right corner) repeatedly until the clock appears in the display. Use the arrow keys (Skip/Back or Left/Right) on the right hand side of the radio to select a segment of the time to adjust. Use the Up/Down arrows to set the current time. Repeat choosing the time segment and adjusting the time until both the hour and minutes are correct. Press Band or press and hold the Audio button to exit the clock setting mode.
ManualsLib has the manual for the Pioneer DEH-1500 here: https://www.manualslib.com/products/Pioneer-Deh-1500-Car-Cd-Player-Mosfet-50wx4-Super-Tuner-3-Am-Fm-Radio-3432555.html
. See page 16 for the clock setting procedure: https://www.manualslib.com/manual/129844/Pioneer-Deh-1500.html?page=16#manual
. See page 6 for the picture of the front-panel buttons for the DEH-1500.
I hope this helps. Please add a comment with the model of the car radio if the above procedure doesn't work for your unit.