Only a team's Leader or Team admin can change roles in the team.
Change a role
Go to the team the person belongs to.
Go to Members & Settings.
Find the person in the list and click Change role.
Choose the new role.
Click Confirm.
Roles
Member: contributes to the team by creating and completing Key Activities.
Team admin: manages team settings and members, but has no visibility into subordinate teams.
Leader: has full visibility into their own team and all subordinate teams.

