When making a scatter plot or any other type of graph it would seem potentially useful to be able to have the user manually input whatever labels they want, rather than trying to finagle the system into finding whichever box may have the title in it. If the legend labels happen to be numbers themselves it gets even more confused and refuses to cooperate… Just make an option to manually input labels… it would make life far more simple.
The related enhancement request is fdo#66339. The expectation is that the required data, to be displayed in a legend entry, is present in a cell somewhere. Thus, to change a legend entry the Name cell reference, for the Data Range in the Data Series, is edited. This is not as obvious to all users as it could be. There is (I feel) a valid case for ad hoc legend entries.