There are a few ways to see every user's UserID:
1. The easiest way is probably just to add the UserID as a column header and sort by it, then you can look for the number that EIOBoard is saying is taken:
2. Alternatively you sort by UserID in the Users Section of the Desktop Application Admin for all the UserID's on one page and without having to change your view. You can also check both Users and Visitors here to make sure the ID isn't being used by a Visitor.
3. To do it by running a report, you can run the Phone List report for a report that has every User one time, then add UserID as a column(then sort by it) for a list of every User's UserID.
4. If you have the Kiosk or Mustering Software, you can also put in the ID to see who has it, then go to the Web to find that User to either delete them or assign them another ID. You may have to check 'show disabled users', or look between both Staff and Visitors to do so.