To update your profile picture:
In the top left corner of the page, tap on your profile icon, located right under the Squad's name.
A window will pop-up, with the options 'Profile' and 'Logout'. Click on 'Profile'. Additionally, you can change your online status or change your notification level from here.
You will be brought to your profile information page, at the bottom, you will see the 'Edit' button. Click that.
Next you will see the option allowing you to edit your profile picture or 'AVATAR' at the top. Click on 'Click to change'. Then choose from any pictures on your device.
Finally you will scroll to the bottom of the page and click 'Save'.