formatting text problem

[bkarin]

When selecting text and applying a format such as BOLD the
entire document will become BOLD. If you hit undo it will
then apply BOLD to just the selection. Sometimes, it will
format and CENTER the entire document. Any idea what may
be causing this?

 

[Dayo Mitchell]

See here:

http://word.mvps.org/FAQs/Formatting/WholeDocumentReformatted.htm