As far as I'm aware, you can't with this forum. I was trying to do it for a specific user and didn't find a way.
Using the advanced search, in the "Search threads" tab with the "Display results as threads" option, a specific user(yourself in this case) in "Posted by:" will display all threads the user participated in and you can see who started the thread by looking at them one by one, which is the closest solution I found.
If you want to see all of your own posts though, you can easily do it by going to your profile page(click your name and then your name again in the popup) and going to the postings tab there.