Instructions. Open the Apple menu and then click on Control Panels.. Click on the Appearance button. In the Control Panel, open the tab that reads Fonts.. Change the font to your liking for each label and entry field.Note that you can't change every font on your computer at once.lick on the Appearance button. In the Control Panel, open the tab that reads Fonts.. Change the font to your liking for each label and entry field. Note that you can't change every font on your computer at once.