Right click on Desktop and select Properties.
Select the Appearance tab.
Click on Advanced.
Under Item, select Menu from the drop-down menu.
Under Font, change it to Tahoma or Arial or whatever you
prefer.
Next, under Item, select Active Title Bar from the drop-down
menu.
Under Font, change it to the font you want.
Thirdly, under Item, select Inactive Title Bar from the drop-down
menu.
Under Font, change it to the font you want.
Lastly, under Item, select Message Box. Under Font, change it to
the font you want.
Click OK to apply the settings.