Setting up ARC for smart tv - 975 vs 976

Hey gang, I just got through programming an activity for my 975 for using the tv apps and having the audio go through the preamp via ARC HDMI. In the 975 it was simple:
1. Set the AUX input on 975 audio to be "ARC"
2. Program remote activity to turn on 975 and tv, change inputs to "AUX" on 975 and "Apps" input on smart tv.
voila!

However, when I go to do the same on my 976 downstairs, you can't tell the AUX input to be "ARC".

Now I'm not sure what to do to be able to have the 976 process sound from the tv. (I'd rather not go optical or analog.)
Any help would be appreciated.

See page 26 of the manual it has a note which says:

To use the Audio Return Channel with your TV, select “HDMI ARC” with the TV input. This will allow the TV input to use audio from the TV to the HDMI Out 1 output of the Model 976.