To expand on what Dick Rees said:
Press the LR button on the RHS of the console, ensure your on the bottom layer (Ch1-16,) and ch1-4 faders are up and not muted in LR, and the LR master fader is turned up and also not muted (you should be hearing dry vox in FOH.)
You have to get the channels to feed the FX sends, (which feed the FX processors.) This is just like getting a regular input channel into a mix.
Press the “FX1” button on the RHS of the console. Faders 1-16 now represent the ch1-16s’ contribution to the FX1 send (which feeds fx processor1.)
Push up faders for ch1-4. Ensure the master fader on the RHS of the console is up around unity (the FX1 send master, if it’s down at -inf you won’t hear anything.)
Press the “FX2” button on the RHS of the console. Faders 1-16 now represent the ch1-16s’ contribution to the FX2 send (which feeds fx processor2.)
Push up faders for ch1-4. Ensure the master fader on the RHS of the console is up around unity (the FX2 send master, if it’s down at -inf you won’t hear anything.)
Now you’ve got your vox channels feeding the FX engines. Now you need to get the returns from those fx engines into the right mixes (like regular input channels.)
Press the “LR” button the the RHS of the console. Go the the Top layer (St1 - Mix9-10 Master.) Faders #4 and #5 are the stereo returns from FX engines 1&2. Their levels indicate their contribution to the currently selected mix (LR.) Raise them to hear the FX in LR.
Press the “Mix1” button on the RHS of the console. Faders #4 and #5 are the stereo returns from FX engines 1&2. Their levels indicate their contribution to the currently selected mix (Mix1.) Raise them to hear the FX in Mix1.
Press the “Mix2” button on the RHS of the console. Faders #4 and #5 are the stereo returns from FX engines 1&2. Their levels indicate their contribution to the currently selected mix (Mix2.) Raise them to hear the FX in Mix2.
A couple of gotchas:
Ensure the FX processors are setup as Mix-Return, and the FX1 engine is being fed by the FX1 send (do the same for FX2.) Press the FX button next to the touchscreen, tap the relevant FX tab and go to Back Panel. I’m looking at GLD Editor ATM, but I’m pretty sure the process is the same for the Qu. The “Front Panel” button on the FX page is where you can configure the FX to be a reverb or a delay etc.
The FX sends are fed post-fader from the input channels. If the channel 1-4 faders are down in LR, they won’t feed the FX engines. If you mute ch1-4, they’ll stop feeding the FX engines.
Very few vocalists like delay on their own vocal in their monitors (especially those on ears,) but they do like a bit of verb. I wouldn’t be surprised if the band wanted less delay in the monitors. Still, horses for courses, give your band whatever they need to play well, if it is some delay in their monitors, then so be it. No one will care as long as they sound good.
It may be worth using the custom layer and arranging the FX returns (or their sends, depending on how you like to mix) next to the vocal channels (or their DCA, if you’re using one of those,) to save you changing layers all the time.
It might also be worth assigning one of the softkeys to a tap tempo for your delay FX. It may also be worth assigning the FX returns (and/or sends) to a mute group, (or DCA) and assigning control of the mutegroup to another softkey, that way you can mute the FX between songs with one button press.
HTH