How to change display picture?

Once your app is live, go to Dashboard>app's Profile Settings to change the display picture.

Note: As per WhatsApp Guidelines, you need to scale and crop the profile photos to be a square with a max edge of 640px and max size of 5MB before uploading. Images with a height or width of less than 192px may cause issues when the resizing occurs, because of this, an image size of 640x640 is recommended.