I know I asked this question before, but (sigh) I cannot find the
answer now, when I need it of course.

How can I select a series in an Excel chart (XY Scatter) using the
keyboard, not the mouse?

The issue is: I have overlapping series, so it is difficult for me to
select a series by moving the mouse cursor to a point in one series and
right-clicking it, as I normally do.

Someone once mentioned a ctrl and/or shift key combination (I think)
that would allow me to select each series explicit in round-robin
fashion. That is what I am looking for again.

More generally, how could I have found the answer to that question on
my own?

Perhaps an Excel Help page. I do not see what I am looking for in the
"keyboard shortcuts" Help page.

TIA.