To edit users:
you either must have the system role "admin" assigned
or you should have the "Manage users and roles" user role permission
Perform the following:
In the bottom of the navigation pane, click Settings.
Click the Users tab.
Click a team member. The user profile appears.
Click on the team members avatar, a pencil icon appears and the page to
change the users photo appears.
Once picture is selected, click Update Photo.
Change a user profile picture through People >Employees
Change a user profile picture through My Profile