How can I change the font size of plot tick labels? - MATLAB Answers ... 1) To change the font size of all texts included of (ax) axes, such as y- and x- axes labels in addition to the title or any other text like tick labels: ax.FontSize =. 2) To change all the text attached to one specific axis: (tick labels and label) ax.XAxis.FontSize =. 3) To change only the size of the label: ax.XLabel.FontSize =.