Hi,
Word has no inbuilt capacity to do this - it can only do this for the whole
of a document. And, when you think about it, there could be many
interpretations of how it should manage 'changes' that result in
repagination, reformatting, etc.
However, if you use the 'Track Changes' feature, Word can store the details
of all changes, down to the character, by user name, date and time. In Word
2000, moving the cursor over the changed text will cause a text box to
display, showing who made the change and when. Other versions may differ.
You could possibly write a macro to pull out the date & time of each tracked
change on each page and paste it somewhere. Putting it in the footer would
be problematic, though, since footers are intended to replicate on all pages
unless you break each page into a separate section. Do that and repaginating
the document becomes a nightmare.
Cheers