Installing Plugin: Optimal Title

I have installed and activated the Optimal Title plugin and followed all of the directions for installation, but nothing has changed on my website. What am I doing wrong? I would like my page title to show first and have the vertical line separator and then the title of my website. I have this very same plugin installed on my first website and it worked, but for some reason, with my new website it’s not working. Any advice would help please, thanks.