When searching you can change the time range (ie 'Newer than 6 Years' and 'Older than 3 Years') to find older posts but stay within the maximum range of 3 years.
Alternately you can use Google to search by entering the terms, maybe the game or forum name in quotes (to restrict to relevant hits) and 'site:larian.com' in the text box. This is also handy for searching for 3 letter words or acronyms / abbreviations, which the forum search ignores.
