How to completely change your Android device font

MTK Android Users: If you want to change your device fonts completely, you will have to root your phone in the first place,back up your Android smartphone with Nandroid.

Requirements 
You phone must be on Android 4.0 and over
Phone must be rooted
Back up your phone with Nandroid
You must have a Custom Recovery(CWM, Philz, TWRP) to flash fonts click here

Note Make sure you do have these requirements

How to flash you device fonts 

Download any font you desired from the link and copy the zip file to the root of your SD Card (the zip shouldn't be in any folder)
Reboot your phone to Recovery mode
Flash the downloaded font in zip
Reboot your device
And bam your fonts have changed.

Download the fonts from this link http://adf.ly/1L64V2
Additional link 355-flashable-zips-by-gianton  Here
LG g2 Fonts link.Here credit - # XDA

Note do at your own risk, but i tell you once you have those requirements you want have any problem.