newtonsongbird on "[Plugin: WordPress SEO by Yoast] Post title tag issue, sitename not showing up"

I think the person in the link you cite above is saying that on the actual post page for that post, he put a custom SEO title in the SEO section and that overrode the settings on the main SEO settings page. Each post and page has its own SEO settings box, and apparently that will override the main settings. You should check that in your instance to make sure that's not the issue.