To adjust the default fonts within word follow these 5 steps:
1)Make sure all programs are closed
3)From the top bar, click on Format > Font
4)In the window that pops up make changes to the font information you want to adjust:
5)Click on the Default button and then OK to save your changes.
This will make changes to the main Word default document. If you use other templates such as Fax coverpages, you will need to load those templates and perform steps 3-5 again.