Personally, I find the search built into vBulletin (the forum software that this site uses) hit and miss, so I often use Google searches on forums. For those not familiar with searching only on one site with Google, here's how you do it.
Let's say you want to do a Google search on this forum for the term freedom or maybe freedom problems, here's how you would do it.
site:http://www.thorforums.com/forums freedom Problems
You would type that full line into either the Google search page or the area at the top of Chrome (might work on other browsers) where you can enter a website address. by adding site: before the http, it will restrict the google search to only that one website, or forum in this case.
Then, let's say you want to only focus on recent posts, you can limit the time frame. When the google search results come up, you can click "tools" and then change "any time" to the time frame you want.