Just to clarify you are right clicking on the text value in the legend, selecting "Edit Axis Label" option, then typing in the new value in the Displayed Label section.
And you do not have save data with report on.
I think each time you open the report it has to recalculate the value for the legend and therefore it will not keep any of your overwritten text in it.
I think you can over write the Chart Title and Axis titles and they will stick but not the legend.
Edited by DBlank - 05 Feb 2010 at 2:38pm