OK this REALLY made me do a facepalm.
I was wresting again with SSRS (Microsoft’s SQL Server Reporting Services), and was just trying to format the numbers in a pie chart. It seemed clear enough: right click on the little numbers in the pie chart and edit the number format. It even displays all the numbers in all the pie slices with the new format.
That change only affects the first series, with no obvious way of selecting the other series values to format them… since they look like they’re already formatted!
Turns out you have to move the next series to the top position in the “Chart Data” floating tool window, and then you can modify the values. I found the answer here on Stack Overflow:
i had this same issue, if you just use the arrows (little blue arrows at the top of the chart data box) to move the value to the top of the list you can edit the label details/code/expression etc for that series. then just repeat this for all the values you’ve added. i’m sure there’s a better way but this worked so that’s what i did. It seems that when you are editing a label it is only ever editing the item/value at the top of the list, after you’ve done your labels then just shuffle them back into the order you wanted them listed
Once you do this, you see new values, unformatted (or, more accurately, formatted with the default number format).
You can then go through the same process as before and change the number format for those data points in the series.
What a pain.