Using the options below, you should be able to narrow your search results down to useful results, without having to wade through a bunch of irrelevant search results.
(https://s15.postimg.cc/ghr4mo1nv/search.png)
The blue circled search box is a thread search. When inside a thread (http://en.wikipedia.org/wiki/Internet_forum#Thread), you can use this box to search for words inside that thread.
The red circled search word is the main search function. This is a dumb search. Enter a word here, hit search, and it will list all posts containing that word.
The green circled Advanced search is where the real power lies. See below.
(https://s15.postimg.cc/w38g6m5wb/advanced_search.png)
This advanced section, opens up some more useful search features.
You can search for words by a user, simply enter the forum username.
Define the search order.
Search in the topic subjects only. ie: Thread titles.
Define the age of the posts to search. ie: Only search for the word in posts not older then 3 days (or 5 days, or whatever you define).
The red underlined option also allows you to define which sections of the forum to search. See below.
(https://s15.postimg.cc/ffgy44qkb/search_choose_board.png)