Ok go to general settings and scroll down to the messaging and notification section I pasted below and that's were the option is to subscribe to every thread you reply in

Messaging & Notification

Receive Email from Administrators
Receive Email from Other Members
Receive Friendship Request Email
From time to time, the administrators and/or other members may want to send you email notifications or messages. If you do not want to receive email from certain people then you may disable the options here
Default Thread Subscription Mode: Drop down box is here
When you post a new thread, or reply to a topic, you can choose to automatically add that thread to your list of subscribed threads, with the option to receive email notification of new replies to that thread.