Where is that located, mine just shows 5-1 I am currently reporting with a Atlas, was this when you signed Up ? But I replaced the 5-1 reporting to WU with the Atlas, which right after I did the 5-1 stuck on 99% humidity just the nick of time.
Assuming you are logged in to wunderground, select "My Profile" from the upper right corner.
Then pick "My Weather Stations" from the pull-down menu.
You'll get a list of your weather stations. You'll see a gear in the upper right of each station listing. Click the gear and select "edit".
After editing, there is a "Save" button if you scroll down to the bottom of the edit page. Press "Save" and you'll get a "thank you", plus there will a green banner at the top of the page (you'll probably need to scroll up) saying your changes were saved.
The interface is a little goofy there, as it isn't quite clear if your changes were saved or not, other than the green banner at top. The banner disappears after a few seconds, too.