When you create charts, Microsoft Office Excel assigns a default name to each chart by using the following naming convention: Chart1, Chart2, and so on. However, you can change the name of each chart to make it more meaningful to you.
Click the chart that you want to rename.
This displays the Chart Tools, adding the Design, Layout, and Format tabs.
On the Layout tab, in the Properties group, click the Chart Name text box.
Tip: You may have to click the Properties icon in the Properties group to expand the group.
Type a new name.