Hi John,
It sounds like your data is in multiple columns.
(FYI – If you have the data in a long or Flattened format you can create multiple box plots with one command, as in this example. Then your axis will have labels automatically.)
Sounds like what you have something like this, where you have one command per box.
To change the axis to categories for each box, create a text column that has the label you want.
Then edit the Axis settings as shown:
That will give this:
Hope that helps!