If you would like to fit more app tiles into the Start menu of Windows 10, this guide will teach you how to add a fourth column of tiles. The Threshold 2 update for Windows 10 features a new setting called Show more tiles that will allow you to add extra app tiles to the Start menu.
Show More Tiles in Start Menu of Window 10
The first step is to download and install the Threshold 2 update for Windows 10; it changes the OS version to Build 10586. Once done, click on Start > Settings and then navigate to Personalization > Start: