If the Use System Fixed Width Font option is selected on the General tab of the Terminal Preferences dialog, the terminal uses the font size that is specified in the large print theme that you selected. However, if the Use System Fixed Width Font option is not selected, click the font selection button to increase the font size that is used to display text in the terminal.
If the Use Default Theme Font option is selected in the gedit Preferences dialog, gedit uses the font size that is specified in the large print theme that you selected. However, if the Use Default Theme Font option is not selected, increase the font size that is used to display the contents of the gedit text editor window.