You may change the Salesperson for a selected document or documents. Salespersons can be changed for posted as well as unposted documents. 

To change the salesperson on documents: 

1.On Documents (Documents list) (Action ribbon), select the Document type, if the correct document type is not selected.

2.Select the Document(s), right-click on "Salesperson" context menu and select "Empty" or the salesperson from the sub-menu. The Salesperson will change on documents and the reports. 

If you need to select multiple documents, press the Ctrl or Shift key and click on each document, for which you need to change the salesperson.