1. Find "Advanced"
Slide two fingers down the display starting from the top edge of your mobile phone.
Press the settings icon.
Press Network & Internet.
Press Mobile network.
2. Select network
To select a network automatically, press Automatically select network.
To select a network manually, press Automatically select network to deactivate the function. Your mobile phone searches for networks within range.
Press the required network.
3. Return to the Home screen
Press the home icon to end the session and return to the Home screen.