You can change your email both online and on the apps.
In the app, once you have logged in, you can change your email account from the main menu of the app. Click on “Menu” and under your name, click on “See or edit profile”. Then you click on “My Data”. On this screen, you can edit the email address field by pressing on (add the symbol)
On the website, access your account with your username and password, go to "My Account" > "My Data" and you can change your email by clicking on (add the symbol)
If you change your email address, you will receive an email at your current address to confirm the change.