To change your voicemail password, you must know your current voicemail password. Note: If you have forgotten your existing voicemail password, you will not be able to access Voicemail until you reset your voicemail password.
From the home screen, tap Apps.
Swipe to, then tap Visual Voicemail.
Press the Menu key.
Tap Change Voicemail Password.
Enter the current voicemail password.
Tap the Voicemail password field, then enter the desired new voicemail password.
Tap the Retype password field, then re-enter the password.