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Then, as Enterprise Admin, go to Enterprise → Admin and select the Users tab close to the top (between Enterprises and Certificates). Select the appropriate user from the list presented (which will include all show users with emails under your domains).

2025-01-23: The list will not show all users (only the first 20?) and you need to use the down arrow to load more or use the filter function. Be aware that the search box only searches among the already displayed users.

In the pane shown for the selected user, select the Account info pane. You can select to additional roles for the user:

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