Unless you set a profile picture for a team, the team profile picture will match the organization's profile picture.
- In the top right corner of GitHub, click your profile photo, then click Your profile.
- On the left side of your profile page, under "Organizations", click the icon for your organization.
- Under your organization name, click Teams.
- On the Teams tab, click the name of the team.
- At the top of the team page, click Settings.
- Click Upload new picture and select your desired profile picture.
- Click and drag to crop the image as needed, then click Set new team avatar.