
LG G4
Find "Manage contacts"
Press the contacts icon.
Press the menu icon.
Press Manage contacts.
Select option
Select one of the following options:
Copy contacts from your SIM to your phone, go to 2a.
Copy contacts from your phone to your SIM, go to 2b.
Copy contacts from your SIM to your phone, go to 2a.
Copy contacts from your phone to your SIM, go to 2b.

2a - Copy contacts from your SIM to your phone
Press Import.
Press "SIM" below "From".
Press "Phone" below "To".
Press OK.
Press Select all.
Press IMPORT.
Press YES to confirm.
2b - Copy contacts from your phone to your SIM
Press Back up.
Press SIM.
Press OK.
Press Select all.
Press EXPORT.
Press YES to confirm.
Return to the home screen
Press the home icon to return to the home screen.