To change your pin code

you should enter the settings menu 

under “Account” and press “Change pin code”

You are first asked to enter 4 digits of your current pin code.

Then you can enter your new four digits pin code. 

You have to re-enter the same numbers again to confirm. 

If the numbers are the same the pin code is now activated

If you want to cancel press the “Back” button on Android and the “Cancel” option on iOS