Word applies local formatting changes globally. Why?

[Guest]

When I format paragraphs locally in MS Word (make a paragraph bold, or bullet
it, etc), Word automatically reformats the entire document to match the new
'style' of the paragraph. I can undo it, and the formatting remains for the
paragraph I was trying to format while the rest of the document returns the
way it was. But the whole process adds time and if the change isn't dramatic,
I sometimes don't notice that the whole document has been messed up until
later. What's going on?

 

[Jay Freedman]

When I format paragraphs locally in MS Word (make a paragraph bold,
or bullet it, etc), Word automatically reformats the entire document
to match the new 'style' of the paragraph. I can undo it, and the
formatting remains for the paragraph I was trying to format while the
rest of the document returns the way it was. But the whole process
adds time and if the change isn't dramatic, I sometimes don't notice
that the whole document has been messed up until later. What's going
on?

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