To change your account data (login, email or PIN), please tap the portrait icon in the top right corner of the lists manager: 

Select "Edit":

You will be redirected to the website. Please log in to your account using your current login and PIN at the webpage that appears:

Enter the desired new login, PIN or email (you can edit several entities at a time) and tap "Save":

You will be asked if the page should be opened in the app. Select "Open". You will be redirected back to the Buy Me a Pie! app.

If you see the Authorization Failed error, select "I already have an account" and log in to the app with the new data. 

Important! If you are using the same account on several devices, please re-log in to your account on all these devices after changing your data in order to activate the changes and avoid synchronisation problems.