Bold or Underline one word, changes whole document?

[qsy]

When I highlight and change one word or a line into bold or underline, the
whole document is changes, not just the highlighted section?

 

[DeanH]

Turn off "automatically update" as described in
http://word.mvps.org/FAQs/Formatting/WholeDocumentReformatted.htm
Hope this helps
DeanH