I set a fixed-width numeric value in "Style & Configure Layout," saved changes, but am still getting fluid layout on site. All other settings I've done have worked. I've created several sites using Atahualpa & never had this problem before. Am using latest versions of Atahualpa & WP. Please advise. Thanks.

I don't completely understand what's going on, but I suspect the culprit was the SmallBiz theme. I'd activated it for just a minute to check it out, but it appears when I deactivated it & activated Atahualpa instead, SmallBiz apparently left some stuff behind, creating several problems for me. I eventually wiped the slate clean - uninstalling & reinstalling WP & starting over. Now I have the fixed-width layout w/o problem. Maybe this info will help someone experiencing similar problems.