Click on "Account Details" rather than Preferences for the line immediately beneath your avatar name.
I'm not usually slow, but Account details has email, email options, the avatar, date of birth, options for that, location, website, gender, occupation, about you and "identities".
I'm not seeing a way to change the line immediately beneath my avatar. I remember it in the past, but think that was the previous forum generation. I also have an issue where when I de-select the show day and month of birth, when I save, it deselects the show year of birth as well.
I previously looked thru all of the various profile areas w/o finding a way to change the line immediately under the avatar.