From the home screen, tap the Apps icon. Note: If you have forgotten your existing voicemail password, you will not be able to access Voicemail until you reset your voicemail password.
Swipe to, then tap Visual Voicemail.
Press the Menu key.
Tap Settings.
Tap Change voicemail password.
Enter your existing voicemail password, then tap Continue.
Enter the desired new password, then tap Continue.