Right-click your desktop in an open area, free of shortcut icons.
Select "Properties"
Click the "Appearance" tab
Click the "Advanced" button
Click on the "Active Window" bar in the picture window, or select "Active Title bar" in the dropdown box labeled "Item:"
Set size to 18 (default) or whatever size you like.
Set Font size to 8 (default) or whatever size you like.
Click Ok to exit advanced properties, click OK again to exit properties.
Change is immediate.