Hi Brian,
I don't think any of us really get to master our instruments fully ... even the most accomplished performers are constantly discovering new things about their keyboards ... we tend to intentionally learn about the parts that we gravitate towards ... and anything else is usually a serendipitous discovery ... well it is in my case
Reliance on the user manual is a non-starter in 90% of cases as they are habitually written in 'outer mongolian' or 'klingon'
This is where forums, or should I say 'fora', like our own come in to play ... even the most difficult problems can be solved with help and advice from some of the most knowledgeable keyboard users/software writers of the international keyboard community ... Jørgen Sorensen, Michael Bedesem and Andy Gilbert to name but a few who look into forums, some more often than others, but these folk willingly offer their time to help us when we get stuck with a problem.
And of course there are many regular hobbyists who have built up an excellent working knowledge of their favourite range of instruments, like Eileen Lowry ... who will go out of her way to help anyone in all matters relating to Yamaha - particularly the Tyros series ...
But in all honesty Brian, your own last resort ... "just pressing buttons to see what happens" works fine for me
A great post ... I do hope it get some replies
All the best ...
Mike