why do i "sometimes" need to "edit chart object" before "source da

[Flirty and Blonde]

More often than not I can right click on a graph and "source data" or modify
the chart title. Sometimes though, I have to right click > "edit chart
object", and then I may right click again to do the editing I want. Why do I
need the extra choice of "edit chart object"... and why am I presented with
that on some graphs but not all? Thank you,

 

[Luke M]

If you have grouped something with your graph (such as a drawn line, text
box, etc) then XL treats the whole group as a picture/object, but it is still
smart enough to realize that rather than ungroup everything to change the
chart data, you may just want to directly edit the "chart object".