The chart title and subtitle, the axis title, axis label and the legend belong to the texts that can occur in a chart.
You can format the texts by changing the following properties:
Defining Global Text Settings
You can set the font for all the texts of a chart at one time.
The font that is set is valid for all the text elements that do not have their own text formatting, i.e. for which the property Font is set to Automatic.
Defining Local Text Settings
You can manually format text elements whose appearance should differ from that defined by the automatic and global settings.