All users in the workflow must have a user name. This identification reveals who has checked out a particular file and makes this information available to other users. It’s also required in order to check out a file for editing.
If you’ve already specified a user name and want to change it, you must check in any content you have checked out. Otherwise, changing user identification during an editing session would forfeit your ability to edit content that you have checked out—it would be checked out to you under a different name.
User identification is application-specific; no single user can have multiple user identifications per application.
Choose File > User.
Choose User from the Assignments panel menu (Window > Assignments).
If you forget to specify a user name using this method, you’re prompted to enter one when you attempt your first workflow action.