I just installed Atahualpa 3.6.7 here - http://elizabethedwards.me/

The first thing I did is go to Style & Configure Sidebars and uncheck all the boxes for the left sidebar. I clicked the big Save button, refreshed my site, and the left sidebar was still there. I tried again, and again. What am I doing wrong?

SOLVED: still no idea what happened, I reset the options and unchecked the boxes again, and this time the left sidebar went away.

It could have been a caching issue and you were seeing the old page

It looks like you don't have the 3.6.7 PATCHES applied. Here are the links.

• PATCH 367-01: Odd effects when 'CSS: Compress' = 'Yes'
• PATCH 367-02 is incorporated in PATCH 367-04
• PATCH 367-03: PHP errors when adding widget areas in index.php
• PATCH 367-04: Hovering over a Post/Page title only shows "Permanent Link to"
• PATCH 367-05: Site Title appended after the 'WordPress SEO by Yoast' title