[Richard Crowley]

"Tilsip" wrote ...
With a 6.1 surround a/v receiver, what is the best setting for
listening to TV programs, i.e. surround, stereo etc?

I find w/ the surround setting, the volume jumps all over depending
on program, commercial being played. On other hand, many programs
sound better in surround.

There is no "best setting" because the different programs
were all designed, mixed, and encoded according to the
whims of the people who produced them.

You appear to have already discovered that different
decoding settings at your end appear to correlate to
the way the programs were produced (and/or with
your listening preferences).