Hi Timothy,
I have updated your email as requested.
The problem is, that the plugin has no effect on the page title there whatsoever, it is a theme related issue, usually it is hard coded into the theme’s header.php file. The code you have, will only work if the document title is properly printed there, and there is no .htaccess override active from any source.
Instead of using custom codes, I would suggest trying the YOAST Seo plugin. It’s free, fast, and is pecifically made for this. I believe it has the feature to construct .htaccess rules to override the page titles on the results page as well as archive pages etc.., and it’s also a nice addition to your site. It gives you a better page title/seo options overall.
If the custom codes and the plugin does not work, then you might have to contact the theme author to ask what might be going wrong there. The custom codes you have there should work though, they seem to be correct.
PS.: I tried to log-in via FTP and SFTP as well to check, but I got a password authentication error every time.