From the pinned FAQ in this forum.
Q: How do I see the topics that I posted in?
A: All subforum indexes have a "Show All" -> "Topics: I Replied" link in the drop down box at the bottom, there is currently not a global search for this feature.
Also if you go to "My Controls", then on the left select "View Topics". It will show all of the topics that you have posted in (after 10 days of inactivity, they are removed from this list).