1. Find "Network operators"
Slide your finger downwards starting from the top of the screen.
Press the settings icon.
Press Network & Internet.
Press Mobile network.
Press Network operators.
2. Select network automatically
Press Automatically select network.
3. Select network manually
Press Search networks and your phone will search for networks.
Press the required network.
4. Return to the home screen
Press the Home key to return to the home screen.