Dell U4323QE KVM Question

Is there a way to transition from screen 1 to screen2 which would be the PIP PC with your keyboard and mouse. Currently I have to open display manager and click usb source to switch my keyboard and mouse to the PIP Computer. Then I have to open the display manager on the PIP PC and do the same thing to return. I would like to transition between the two as their is an option but its grey out. Both units are Dell PC's with current display manager installed.