An axis title is a word or phrase that describes an entire axis. Titles generally define what kind of data is being shown on that axis. The text of axis titles always displays horizontally, even for vertical (Y) axes.
To add or edit an axis title:
Axis titles share font and color information with axis labels. You can't make axis titles and axis labels look different. For information on changing the color or font of axis titles and labels, see Changing Fonts, Font Styles, and Font Colors.
