Once you've inserted a chart into a sheet, you can make various changes to it. You can change the chart type, switch rows and columns, change a chart's title, and change a chart's legend.
Different types of charts are better for presenting different types of information. For example, a column chart is great for comparing values of different items, but not for illustrating trends or relationships. If you find that a chart you've created isn't the best fit for your data, you can switch to a different chart type.
The chart title often appears above the chart and is used to describe the data that's being presented. You can add a completely new chart title or simply change the text of an existing one.
Click the Customize tab in the Chart editor pane.
Click the Chart & axis titles section to expand it.