tls49, My daughter's Panasonic does not have menu selection. None of Panasonics in ABT Electronics store had it. Same for LG. We checked manuals with specialist in the back of the store. This problem with Panasonics was mentioned in many threads. Below link to manual of new 4K Panasonics TVs:
ftp://ftp.panasonic.com/television/ehelp/tc-55cx800_en_ehelp.pdf
On p.54 it states that:
ftp://ftp.panasonic.com/television/ehelp/tc-55cx800_en_ehelp.pdf
On p.54 it states that:
When ATSC channel is selected, the output from DIGITAL AUDIO OUT jack will be Dolby Digital. When NTSC channel is selected, the output will be PCM.

