you aware that you need root for that, right?
I use two tools for that. Changing the DPI for the whole system can be done for example using Rom Toolbox Pro. (Performance -> build.prop Editor -> swipe to the left -> LCD Density)
This actually brakes Play Store, therefore i use the app settings module for xposed framework to give that specific app the original DPI so that i can download updates and stuff.
current Phone: HTC One Silver / SlimBean 4.3 Beta / stock Kernel / S-OFF / SuperCID
current Tab: Nexus 7 (2013) / SlimBean 4.3 Beta