If you wish to change your passcode, swipe to the Settings of your App where you will see the Set Passcode icon.
In there, you will see the option to change your log in code - once you press that, you will only need to confirm the new code and it will immediately be changed.
If you wish to change your Signature, which allows your to confirm significant actions, go to the Settings of your myTU App where you will see the Set Signature icon.
Once you press on it, you will be able to create a new sequence - make sure it connects at least 5 dots. After you repeat the pattern, it will be changed immediately.