Search function question...

Guys,

Do any of you know how the search or advanced search functions work? I couldn't find old threads of mine so i had to look manually one by one throughout all my threads until i found them. Besides it's weird because if i put a word named in the title of that thread it still doesn't find the thread in the search or advanced search functions. I have tried every and each options, even looked from 1 year until today and nothing.
But, what's even more weird is that once i found the thread, i bumped it up, sarched again for it using the common search function and it found it, really weird!!! It seems like if a thread has been stored for a long time without no one posting there, it seems like if that thread doesn't count when searching for it, it doesn't matter if you use the common or advanced search. Once you post on it again, bump it up, etc., it's like you make that thread "come back to life again" (literally) and then, if you do a search for it, you have no problem to find it.

So... do you know how to find really old threads?

Another weird example is that if you search (for example) for the word "list", it only finds (for example) 20 threads with that word..., i can't believe that the word "list" is only written in 20 threads if AO has thousands of threads, know what i mean?

How does it work?

Thanks,

DKRR