If you need to change your email address on the Withings App for iOS, follow these steps:

1. Open the Withings App.
2. Select Profile.
3. Select the Settings Gear Icon in the upper-right corner.
4. Select Account & Security.
5. Select Change Email.
6. Enter your new email address in both fields and click on Update my Email.
7. You will receive a confirmation email on the new email address to validate the change.
   Note: The link is valid for 1 hour.
8. Click on Validate.

Once validated you will be redirected to a web page telling you the new address is validated. You will also receive an email on your old address confirming the change.

Note: You can only change your email address if you log in using your email and password; it won't work using Google Sign-in or Apple ID, as the option won't appear.