You have your choice between no email notification, instant email notification, daily email notification, or weekly notification. Click on "user control panel" above and then from the left column on that page select "list subscriptions". It will show you what you have each subscribed thread set to. If you want to change one from weekly to instant, click the box to the right of that thread title, then go down to the bottom drop down menu and select your new choice.

If you want to change the way they work for you from now on by default click "edit options" and change it on that page.

Best of luck.