You can search for a specific topic by typing a word into the Search term text box. The window contains an alphabetical list of index terms.
If the cursor is in the index list when you type the search term, the display will jump directly to the next match. When you type a word in the Search term text box, the focus will jump to the best match in the index list.
The index and full-text searches always apply to the currently selected LibreOffice application. Select the appropriate application using the list box on the help viewer's toolbar.