Folks -- Since nobody from Verizon responded to me, I decided to take matters into my own hands and research this problem which, obviously, a lot of people experience.
Here is a thread on this forum from December 2010, titled "STB Won't Keep Settings." -- http://forums.verizon.com/t5/FiOS-TV-Technical-Assistance/STB-won-t-keep-settings/td-p/259467. The problem appears to be common for any Verizon FiOS STB hooked through an AVR and appears to have been around for nearly 18 months.
There is a more revealing thread from January 2012 in a forum called "HighDef Forum" -- http://www.highdefforum.com/verizon-fios/133459-sd-override-keeps-resetting.html. The answer is clearly explained in post #3. In case you can't get to the other forum, here is the text to the "smoking gun" explanation:
"The STB is renegotiating the resolution causing the change in the SD override setting. If the TV is turned off before the receiver, the STB negotiates with the receiver's native resolution, likely 480i like most. The solution is to ensure the receiver is off before the STB and TV.
This HDMI re-negotiation situation appears to be mitigated in IMG 1.9a."
So, the answer for all of us is that we have to shut off our receivers before the FiOS box if we don't want to have to keep re-setting the HDTV every time we turn it on.
I don't know what IMG 1.9a is, or whether or not it applies to us. It's too bad that Verizon just didn't 'fess up and tell us to make sure we switch our receivers off first. I suspect this doesn't happen with Comcast or DirecTV STBs, which is why they are less than transparent about this to their customers (i.e.: us!).
Hope this helps everyone, or makes you more angry.
