Hi Arthur,
As Dean pointed out, you can use Find/Replace to do this, but I'd like to
add a few details that you might find helpful. You can find a word, say
"glossary" at the beginning of a paragraph by searching for ^pglossary, but
bear in mind that the search will select the carriage return at the end of
the previous line along with the word that you want to find. Since you don't
want to change the text, you must repeat the complete search string in
Replace With. With your cursor in Replace With, click More, click Format,
click Style, and select the style that you want to apply to the search
string. Here's where the fact that the search selects the carriage return of
the previous line becomes important. Since this carriage return is selected,
the style will also be applied to it. If you select a character style, there
is no problem, but if you select a paragraph style, the style will be applied
to the previous paragraph along with the entire paragraph containing the word
in your search.
Also, after you run a Find/Replace with options selected on the expanded
dialog box, you should run another Find/Replace with those options cleared.
Otherwise, you might end up applying the style in all future Find/Replace
operations.