Desktop:

To update your photo select [Members] from the main menu and click [My Profile] or click your name at the top right corner of the screen and select [My Profile] in the popup.

At the left top of the screen click the [Browser] button and find the image file on your hard drive.  Click the [Save] button at the right bottom to save your changes.

To replace or delete an existing photo, follow the steps above and click the [Delete Photo] button.

Mobile App.
Tap on “My Account” and tap the avatar icon.
You’ll prompt to either take a camera shot or upload a photo from your phone’s library.

Once you do either, tap the [Save] button at the bottom of the form.
To replace or delete an existing photo, tap the [Remove Photo] button.

For better visibility, make sure the photo is a close shot of your face.