The SIM card must be locked (SIM PIN enabled) in order to change the current SIM PIN.
From a Home screen, tap Apps (located at the bottom).
Tap Settings. If unavailable, tap the Dropdown menu (located in the upper left) then tap Alphabetical. If still unavailable, refer to Manage App Icons.
From the PERSONAL section, tap Security.
From the SIM CARD LOCK section, tap Set up SIM card lock.
Tap Change SIM PIN.
Enter the Old SIM PIN (current SIM PIN) then tap OK. The default SIM PIN is 1111.