It’s easy to edit an existing installed font (not my own created font in Font Creator, but it gets difficult once it has to be saved and using the new edited font. FC saves the changes to the newly edited font, but when I go to use the font, the word program won’t allow me too. Do I have to delete the original font and reinstall the new edited font? And/or save the newly edited font under a different name? 
You got it!
You can’t replace the bearings on a running engine. Same with fonts.
Take a look at:
http://forum.high-logic.com:9080/t/altering-existing-fonts/950/1