All personal information - including your email address - can be changed by following these steps:
Once you have logged in to Zattoo, you will see a profile icon in the upper right corner. If you move the mouse pointer over it, a menu opens. Go to My Account there. On the following screen you will see your data and can also make changes there.
Steps: Profile Icon > My Account > Personal Information and Password > Change > Save.
This view is only available on a PC, so you cannot make these changes in the mobile apps or in the TV apps.