First and foremost, welcome. And I hope you like us here.
Second, you ARE NOT automatically subscribed to threads that you have posted on. Near the top of a page while viewing a thread there is a tab that is "thread tools". If you click it, a dropdown menu with 3 options appears, one of being "subscribe to this thread".
But as DJ said, you might want to turn off notifications. They get annoying. To view your subscriptions, click "my account" in the bar on the left of the page, then find 'list subscriptions' in the bar that replaces it.