You can set up a new transaction PIN by following these steps:
Click on 'Account' at the bottom right of your app home screen.
Click on the settings icon at the top right corner of the page.
Click on 'Manage Transaction PIN'.
Click on 'Forgot PIN?'.
Input your Bamboo password and click 'Proceed'.
Enter your new PIN and confirm it.
Enter the OTP sent to you via SMS/email and click 'Next' to save your new PIN.