ok - i went into CB User Management and the phpbb tab lists the admin user as #401.
In phpbb_users table, the admin is user_id #2
jos_users, the admin is is #62
I went into the CB User Manager to edit the Alpha3 Forum Profile field and to try changing the phpbb user #401 to user #2 or #62 to see if that would work, but it won't let me save because of a separate issue:
When I try to save the profile, it says "First name and last name required". So i go to the first tab where the additional required CB fields are listed, and fill out the required fields. Then I hit save and i get a message like "This email address is already in use - if you have forgotten your password, click the 'lost password link..." or something similar.
As a result - nobody can edit their profile. These are probably two separate issues, so I'm going to split the profile issue off into a separate post.