Use of Bold, Underline, or Italic changes entire document

[Jim in Cincinnati]

What causes an entire document to become Bold, Underline, or Italic, when
only one work or phrase is selected to be bold, underlined, or italicized?
When this happens, the only correction is the “undo typing†button or
(Ctrl+Z).

 

[Suzanne S. Barnhill]

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