When you sign in as a team member, you use the account owner's Google connection, and the owner can restrict which ad accounts you see. If the owner has set a list of allowed Google Ads accounts for your user, the selector shows only those accounts, and the rest are hidden from you across the entire system. If the list is empty, you have access to all of the owner's accounts. The account that opens automatically also respects this permission: if the last account you used isn't allowed for you, none opens on its own. To get access to more accounts, ask the subscription owner to adjust your permissions in the Team area.