All of your personal account information exists in the Profile section of the desktop app. This can also be accessed online at app.thesufferfest.com. (IOS users will need to access via the web at app.thesufferfest.com)
Click on the letter in the top right corner of the app or screen and select Your Profile from the drop-down menu:
This view is from the desktop app:
This view is from app.thesufferfest.com:
Click EDIT next to your current email, then edit your email address in the box. Click SAVE when you are done.
All of your personal information can be edited from this screen.
From within the iOS app:
It is not possible to change your email or details from within the iOS app. Please log in at app.thesufferfest.com to make these changes.