See http://word.mvps.org/FAQs/Formatting/WholeDocumentReformatted.htm
Also, as a matter of curiosity, in which language version is the Undo button
have a label that translates into English as "Regret"?

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Suzanne S. Barnhill
Microsoft MVP (Word)
Words into Type
Fairhope, Alabama USA
Word MVP FAQ site: http://word.mvps.org
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> When i mark a word and press the bold-button, the complete document gets
> format bold. Pressing button Regret restores it to the intended format, with
> the marked word in bold. Silly, and time consuming. Is there a solution,
> anyone?