I'm giving you a hard time, Wilma. Here's what you need to make sure you're doing:
1. Make sure you're clicking on the word "search" directly above the topic bar:
...and
not using the google search bar near the top of the page. That search bar is to search the entire site, not just the messageboard and will only give you a mess of irrelevant results:
2. If your search is not theatre related, select "Other Boards" from the "Search Board" drop-down menu. This will search the "Off Topic" and "Student" boards, though Lord knows why you'd want to read anything on the student board.
3. This one's especially helpful. Select "Subject Only" from the "Search Options" drop-down menu. This will limit the search results to threads with your search term in their titles -- as opposed to any thread which may make use of your search term. It's almost always advisable to use this function unless the term you're searching for is uncommon, you want to find ALL of the threads in which your term has been mentioned, or you suspect there's a thread on this subject, but it's title does not feature your search term. For example, if someone started a thread on Boyhood, but simply titled it "This is my favorite movie of 2014".
4. Hit the "Search" button and your results should show up below. All that said, the search functionality here is far from perfect and if you're searching for an especially common term, you might have to wade through a couple of pages of results. Don't forget that you can also set date parameters to limit your search to threads from a certain period. As you will see, by following these instructions, I easily found the existing thread for Boyhood. Happy searching!