>>You could save the "changed" document to another name, then compare the two documents to see if there actually are any differences:
https://www.google.ca/search?q=compare+2+word+documents>
>When I made a test by constructing a basic document, I saw that the situation did not happen. It appears this is subject to happen on complex document or based on a specific formatting which might apply.
In some of my standard letters I use date(), I guess this is why I experience the same as you.