How to change your phone from 3G to 4G

How to change your phone from 3G to 4G
•Your phone must be rooted
•Install root explorer
•Search for a file called 'persist.radio.lteon'
•Open that file and change it from 'false' to 'true' save
•Reboot your phone.
You will be able to see "LTE/wcdma/gsm (auto connect)" in network mode.