Did you try opening your profile and opening Notifications and Emails?, If not, try changing your settings there and see if it works.
These are the options you can see and change settings.
Automatically watch topics after replying to them. (You can add all of your posted-in topics to your watchlist.)
Receive forum announcements and important notifications by email.
Receive reply notification only for the first unread reply.
Turn notification on when you post or reply to a topic.
When sending notification of a reply to a topic, send the post in the email (but please don't reply to these emails.)
You can also find these too.
For topics and boards I've requested notification on, notify me of:
Choices:
Moderation only If I started the topic
Replies
Replies and moderation
Nothing at all
You can also see the current topics notifications or boards notifications in the "Notifications and Emails" that you enable.