User on Account Team can't grant access level to new Account Team members
|Knowledge Article Number||000004776|
A user is added to Account Team. That user in turn tries to add another user to the same Account Team, but doesn't have the option to set Account, Opportunity, and Case access levels.
This is by design. The Account owner or any user that has "MODIFY ALL" permission on Account Object would have to add new member in order to be presented with those columns to set object access.