OldPod, if you go to the front page of polyamory.com and scroll down just below the sub-forum listings close to the bottom you will see a link titled 'View Forum Leaders' towards the right middle. Click on it and a page will come up with various administrative titles. Anyone under 'Moderators' can likely help you.
Threads move down the page as newer threads get created, or old threads get new replies, and go to the top. If someone posts to your thread again, it will be at the top of the page again.