Yes you can change the margins in the Normal Template.
Open a Word doc, access your Quick Access Toolbar and open your Styles link. Click on the down-arrow 6 to the right of the Styles icon, and click on Modify. (If you don't have a Styles icon in your Quick Access Toolbar, you can add one by opening the Quick Access Toolbar and clicking on More Commands, and then following the on-screen directions. OR you can go into the Ribbon to Home, go to the Style section, and in the bottom of the Style section, at the far-right, click on the down-arrow, which should open up the same Menu of styles.)
Either way, once you've clicked Modify, when the new screen opens, in the lower-left hand corner click on Format. Then select Paragraph. There you will see all the options to set your margin preferences for your Normal Template.
When you're done, be sure to click the box that makes the new setting for ALL docs in your Normal Template, not just the one you have open.