To edit a chart title that you have inserted into a Office document:
A grey border appears around the chart and the menu bar now contains commands for editing the objects in the chart.
If no title text exists, choose Insert - Titles to enter the text in a dialogue box.
A single-click on the title allows you to move it with the mouse.
If you want to change the formatting of the main title, choose Format - Title - Main Title. This opens the Title dialogue box.
Select one of the available tabs in the dialogue box to make modifications.
Click OK. In your document, click outside the chart to exit chart editing mode.