WPM Recording to Edit

It is possible to make changes, but the way it works is you select an existing step to which you want to then add to the recording from that point. The problem with this, is that it deletes all of the existing actions from that point, as you are required to re-record the whole of the transaction from that point.

In your case, this may be OK if the change is near the end and not much benefit if it is at the early part of recording.

you can also export the action as an xml file, then see if you can figure out how to modify that part of the xml to make the change you can import them back in.