There are a few reasons you may want to change your screens resolution. Many of today's smartphones have 2k QHD displays. Do you really need all of those pixels, or could you benefit in the slight performance boost you might gain from shrinking down your resolution. Not only are you able to reduce resolution for possible performance boosts you can also change the size of your screen. If you are having difficulties reaching the entire screen of a huge device like the Nexus 6 having the ability to shrink the screen and reduce the resolution can really help. The Iphone 6 plus already has a feature like this that allows you to reduce the screen by half for reachability. To grab this app head to the link below.
via XDA