[JW having trouble with Word]

I created a form using a standard document template. The template has
drop-down lists in it. What I am trying to do is protect these fields once
they have been selected. For example, I want to be able to fill the form out,
select the drop-down items that I need, and then save the form as a .doc.
What I dont want to happen, is someone going in weeks or months later and
being able to change these drop-down values.
I tried setting the document to read-only, but when I emailed it to
someone, they were still able to change the drop-downs. Any tips or
suggestions are greatly appreciated.