You can add users with account-wide access, but still retain permissions. This is useful if you have a large amount of workspaces, and wish to invite users to all of them, but still retain their permissions*.
When inside the "Users" tab, select "Add Users". Then adjust the drop-down menus to the level of access and permission you wish the user(s) to have.
*Users invited as an Account Administrator will also be given access to the "Account" tab which includes billing information.
Note: Any user invited to the Account level, regardless of permission level, will automatically become a Paid User. Granting Account-wide access means the user(s) will have access to ALL WORKSPACES on the account, including all future workspaces as they are created.