FX on Specific channels within a Mix

Hi Everyone. Still trying to learn the QU24 board a little better.
I’m currently working with the FX options and trying to figure out how to have the FX only affect a few select channels (i.e. the vocals and not the instruments).
I’ve read teh reference document and Manual, as well as watched all the videos. I believe I’m doing what they say to do.
So the mix of concern (streaming) is Mix7-8 that I need to add some reverb / delay to, and the vocals are on channels 10-12, and I have a digital piano on channel 5 and 6, I’d like the effects to be applied only on channels 10-12.
What I’ve done so far is the following:
I have a reverb setup on FX1, and a delay set up on FX2.
Both are set for Mix>Return and the Input set to Mix 7-8.

I select the FX1 button on the lower side of the board, near the mixes.
I then raise the fader strips on channels 10-12, and the master fader, all to unity, all others are at min.
I then hit the top layer (with the FX sends / returns, etc.), and also select Mix7-8.
I then raise the FX1 Return fader to increase the amount of FX to be applied.
When I go back to the Channel select lower layer and start to raise the faders, I hear the FX on ALL channels in MIX 7-8
What am I doing wrong? I thought that by only ‘sending’ from the select channels to FX1, they would be the only channels to have the FX applied.
Thanks

So the mix of concern (streaming) is Mix7-8 that I need to add some reverb / delay to,
If you add reverb to mix78 you get it on all of mix78.

I would ever ever add reverb to any mix going to livestream. But then I would never add reverb to a live situation either.
But that is just me.

If you only want reverb on the singers and their channels going to livestream then try these links
https://community.allen-heath.com/forums/topic/qu-32-need-step-by-step-instructions-for-adding-reverb-to-1-2-channels