Smart notification option

I want to only get an emailed notification when one of my posts have been answered.I guess this is the  Smart option, but I cannot get to that to choose.Following this :-

click the Profile button found in the top menu bar of the forum, and then click the Edit Profile button on your profile page. You'll then be taken to the Edit Profile & Settings page; once here, click on the Notifications tab.

But this does not get me to

Notification Frequency - Only Applies to Emails

Smart - only emails you once per item on the forum until you've viewed the item you're being notified about. So if you were notified about a thread you wouldn't receive any further updates about that thread until you visited the forum and viewed the thread.

Help please