Yes, someone knows. (Sorry, couldn't help it! <g>)

Use a wildcard search, explained at
http://www.gmayor.com/replace_using_wildcards.htm. That is, click the More
button in the Replace dialog and check the "Use wildcards" box.

If your document uses only straight quotation marks, then the Find
expression is simply

  ("*")

and the Replace expression is

  \1

and press Ctrl+B in the Replace box so the label under it says "Font: Bold".
Then click the Replace All button.

If the document uses curly quotes -- what Word calls "smart quotes" although
they sometimes aren't so smart -- you can use those characters in the Find
expression either by copy/paste from the document or by typing in the ASCII
codes: hold the Alt key while typing on the number pad 0147 for an opening
quote and 0148 for a closing quote. That will give you the Find expression

  ("*")

Finally, if the document has a mixture of straight and curly quotes, you can
try changing them all in one go with the Find expression

  ([""]*[""])

If there are any unmatched pairs of quotes in the document, though, you
could wind up with a very large chunk of non-quotation text in bold. Just
remember that Undo will bring you back to the original state so you can fix
the incorrect quotation mark and try again.