Go to your profile settings page. After signing in, click on ‘Settings’ from the drop-down menu below your profile picture (the circle in the top-right corner of your screen for those who never added an avatar). If you’re on a mobile device, use the drop-down menu from the three-lined icon in the top-right corner of your screen.
Update your picture. Click 'Change profile photo' under your current photo. Choose an image from your device or hard drive and click 'open'. Your new choice will automatically save.
Edit your username or other profile content. Tap or click on any of the fields you wish to edit. The field you've selected will become dynamic and a 'cancel' and 'save' button will appear. Click 'save' when you've made your update to the field.