Okay, took another look. About the only thing that's as enjoyable as studying receiver manuals is the Internal Revenue Code. The provision re "Auto" described on pp.77-78 appears to be independent of the one on p.80. If it wasn't, the one on p.80 would be impossible and "Last" would be nullified by the earlier setting. The pp.77-78 procedure appears to be a way to disregard "Auto", but just temporarily during that session, while the one on p.80 appears to have continuous effect.
What still isn't entirely clear is if setting "Last" applies only to coax and optical("Digital Inputs"?)inputs or also HDMI audio. You could at least try a coaxial cable for audio to see if in fact it stays on "Last".
