I'm guessing most folks are thrown off by the Search box's default search location tracking with their current location within the site (aka Inline Search), and/or the fact that a "search scope" is even being employed, indicated by the menu label on the right in the Search box.
So if someone's already in a specific topic (thread), and they just enter a search string it will default to just searching within the current topic they're in (indicated by that "This Topic" menu label) - likely NOT what they were looking to do...
If you're at the "02 General Discussion" forum level looking at the most recent listing of topics (titled threads), your inline search will default to just searching the "02 General Discussion" forum (indicated by that "This Forum" menu label next to the search box).
To search ALL FAQ Forums at once, just switch that menu label selection to "Forums". This will also include all sub-forums listed under the Forums pull-down menu in the main site menubar (incl. Classifieds and Groups).
One last tip: searching "Forums" will not search the FAQ Technical Articles. To search them - go to that section of the site, then search (you'll see the default search box says "This category"). But note that the "FAQ Article Construction Zone" IS a forum though...
The other aspect of the site search engine that might stumble folks is how multiple words are handled.
The default search "ANDs" the words you enter - and locates results having BOTH words ANYWHERE WITHIN the default focus (topic tiltles and posts). But such results can contain lots of 'noise'. If you know in what you're searching for that the words should appear together, right next to each other as a PHRASE, putting the phrase in "quotes" will only find the words when they appear right next to each other in the content.
Of course, the biggest search failure that almost everyone encounters is figuring out the right search terms/phrases to use!
BTW, I actually always use the built-in site software search vs. google, and I really like the ability the "Advanced Search" screen provides in tailoring how the search works. (Access Advanced Search via the "gear" to the right of the Search box, which takes you to screen with all the bels & whistles settings.)
When I'm looking for stuff I like to play with the results sort order (for example, not 'most-recent' on top, but perhaps "most viewed"), or focus the search only on Topic titles vs. titles and posts) or a particular Date range, or to play with the multi-select Forums selection menu to widen/narrow the search results.
There actually IS a "Searching" entry in the Help Files section of the site, though it's pretty sparse...
... and you'd need to know how to use Search to switch the Search box menu label to "Help Files" to locate it.
Or for many looking for simplicity -- just do what others are recommending: switch the Search menu label to use google's engine...