Most times, Nikon sends me on-line links to support pages, which go a long ways beyond the printed manual. A lot of that information might also be here, in Nikon’s Online Manual::
D780 Online Manual
There are several other links I’ve been given, including this one:
D780 | Digitutor | Nikon Consumer
Most importantly there is this almost-three-hoour video, which explains just about everything about the D780, including all the menu settings, and which to use, and why. It’s the best training video I’ve found about any Nikon model:
https://www.youtube.com/watch?v=hR4CE162H8w
This person also sells a “Crash Course” in how to use the D780, which goes much further.
https://www.michaelthemaven.com/nikon-d780-crash-course-training-tutorial-now-available/
What I’ve learned about this type of links, is not to do anything unless I know how to un-do the change I made. Following the advice in this thread, and randomly making changes just to see what happens, is never a good idea, unless you also know how to restore things to “factory settings”. Try it on a computer, without knowing what you’re doing and why, means you’ll likely be getting back to the computer support people to put things back to “normal”.
For my Nikon, there are lots more links, but I have found these to be the best. Here’s one of the many links my buddy Ken Rockwell posted:
https://www.youtube.com/watch?v=AEfotPYZcoE
Of all the above, the almost-three hour video I posted in my third link is by far, my favorite, and it covers just about every aspect of the camera. It doesn’t cover silly things I might have done without knowing what I was doing, but the almost three-hour video usually helps me get things back to how they should be.
For anything computer related, my best advice is if you don’t know what you’re doing, don’t do anything - and if you go ahead anyway, make sure you know how to put things back to where they used to be. Unless, of course, you’ve got an Apple computer, where Apple Tech Support will take as long as necessary to get your confused computer back to the normal settings. End of speech.
George, regarding what you posted, Nikon and Apple may be unique about this. When I tried to help my brother fix his Windows computer, the first thing they wanted to know was if it was still on Warranty. Ditto for Microsoft, when I tried to help get his Outlook Mail app working again, after a Microsoft update broke it. $$$$$
Both Apple and Nikon send me links to anything they think will help me in the future. And back to Nikon, there books and Books available for sale about many Nikon camera models, especially so for the more “professional” camera models.