Hi there. You can do this on the Qu32: (i’m sure it’s the same for the Qu-24)
1. Select their mix (for example mix 1)
2. Then select the “layers” button
3. Then find FX 1 return, FX 2 return, etc. faders
4. Bring the specific fader up and this will send that effect to mix 1 (their monitor)
Hope that helps.