Color me confused too
If you want to run pure 7.1 AND ZONE 2/3, you will need separate amplification for those zones. To run 7.1 and/or ZONE 2, you can use the internal channels of the rear/presence, I THINK.
You may only get 5.1 and ZONE 2. Zone 3 requires separate amplification either way. Most other brands work this way. I couldn’t find anything in the manuals to help clear this up.
I also want to make sure you are connecting to the zone2/presence terminals in the bottom right corner.
Reference manual as (5790/2500)
T2T is correct, see note (pg 68/78)
The setup procedures for these two units are essentially the same. Don’t take all of this as gospel but these are the steps I would take. Hopefully, you are familiar enough with the setup menus to make this easier.
Pg 53/57 - Select PRch/Presence
Pg 58/63 - Output Vol=Var, Zone2 Amp=On/ Zone2 Amp=Internal, Zone 2/3 Volume=Variable
Unfortunately, the remotes do not come enabled for zone use.
Pg 69/79 - / Use code 2001
This is a quick guide. I hope it helps. Hopefully, other Yammy users can help.