Securing Samsung Galaxy M31 with Lock SIM Card

1. Settings > Biometrics and security

2. Other security settings > Set up SIM card lock > Lock SIM card: Enable

3. Lock SIM card:

    Enter your current SIM card PIN: {4-digit PIN} > OK

4. Change SIM card PIN:

    Enter your current SIM card PIN: {4-digit PIN} > OK

    Enter a new SIM card PIN: {4-digit PIN} > OK

    Enter the new SIM card PIN again to confirm it: {4-digit PIN} > OK

5. SIM PIN changed successfully.