You can easliy change data labels in a chart. Select a single data label and enter a reference to a cell in the formula bar. You can also edit data labels, one by one, on the chart.
With many data labels the task becomes quickly boring and time consuming. But wait, there is a third option using a duplicate series on a secondary axis.
Note! Before you continue reading. If you own excel 2013 or a later version you don't have to do the work-around presented below, just enable "Add values from cells" in "Format Data Labels" settings and select a cell range.
The animated image above shows you dynamic custom data labels. Here is how you build them.
Create a chart
Select a cell range
Go to "Insert" tab
Click "Column" button
Select the first 2-D Column chart
Add another series to the chart
Right click on chart
Click Select data
Click "Add" button
Select a series name, cell C2
Select series values, C3:C8
Plot series on the secondary axis
Click the second series on the chart
Right click on a "second series" column
Click "Format Data Series..."
Select "Secondary Axis"
The following article shows you another trick using the secondary axis in a way it wasn't intended to do: