Choose Platform:
iOS Android Website & Mobile Web
Tap the Settings icon 
located at the top right corner of the PayByPhone home screen.
Select Account Settings and then SECURITY SETTINGS
Enter your current password followed by a new password and confirm.
Tap CONTINUE to change your password.
Tap the menu icon located on the top left of the home screen (3 stacked horizontal lines)
Under My Account select Password
Enter your current password followed by a new password and confirm.
Tap UPDATE to change your password.
Visit https://m.paybyphone.com from the browser on your mobile device.
Click the Account menu in the top navigation bar.
Click SECURITY SETTINGS
Enter your current password followed by a new password and confirm.
Click SAVE to change your password.
Website:
Login to your account at https://paybyphone.com/receipts with your phone number and current PIN.
Click the Profile button and locate the 'Click Here to change PIN' button
If you have forgotten your PIN, you can have it sent to you here.
Note: The system will lock you out for 15 minutes if you try the wrong account number/pin combination 3 times.