It's been years but I think I had that problem when I started. IIRC, changing the setting to "no notifications" only works for future thread subs. Anything you're already subbed to continues to work under the settings it had when you subbed (which happens automatically when you post).
You'll need to clear your thread subscriptions or pull up each subscription and change the settings.
This is all dim distant memory, so details may be different.
Coffee is your friend. Everyone else is an acquaintance.