To edit your profile, go to the app's Settings > [your email address] > Edit Profile.
Your profile will become editable.
From here, you can change your name, birthday, email, or profile image.
To change your profile image:
- Tap on your avatar.
- Select an image.
- Edit the image as desired.
- Tap on the checkmark at the top left to save.
Remember to tap Save in order for all your changes to take effect.