The new Qu should have DCA Spill Function where you can easily see and adjust the channels assigned to a DCA, this function would greatly improve workflow efficency
As a workaround, you can temporarily select the PFL for the DCA bus. All participants of that DCA will blink their PFL LEDs.
When I press the Sel button on any DCA, the input assign buttons appears on the screen. I can now see anything assigned or go ahead and unassigned or assign any other channels. Easy Peasy.
DCA-Spill is something completely different - see also here:
If you would also like this feature, which is obviously not yet available in QU2.0, you can vote for it here.