If you have the latest updated version of Word 2016 (Office 365), click on the View tab and you will notice a new group on the Ribbon called Page Movement.
1. Click Side to Side and you can scroll through your document by using the Horizontal Scroll bar which runs horizontally at the bottom of the Word window.
2. Two tools over you can click on Thumbnails and you will see the small thumbnail pages of your document. Click on a page to go to that page. You must be in Side to Side view to see the Thumbnails tool.
3. To switch to the usual vertical scrolling click on the Vertical tool.