1 Find "Network mode"
Slide your finger down the display starting from the top edge of your phone.
Press the settings icon.
Press the settings icon.
Press Mobile networks.
Press Network mode.
2 Select network mode
Press LTE/WCDMA/GSM (auto connect), WCDMA/GSM (auto connect), WCDMA only or GSM only.
3 Return to the home screen
Press the Home key to return to the home screen.