Some people have the tendency to create such a simple PIN code for their SIM card lock, then later they find out that their kids can easily sneak onto their device and access or change their personal information. If you have already created such a simple SIM card PIN, then it’s highly recommended that you should make adjustment to it before it’s too late.
To change the SIM card PIN, just do the following instructions:
1. First, head to Xperia Z’s Home screen.
2. Here, press the Apps icon.
3. Open the Settings app.
4. Hit Security.
5. Choose Set up SIM card lock.
6. Tap Change SIM PIN option.
7. Next, provide the old SIM card PIN.
8. Hit OK.
9. Then type the new SIM card PIN.
10. Hit OK.
11. Verify the new SIM card PIN one more time.
12. Then tap OK to exit the setup.