Browser tab title is not changing

Hi everyone,
I’m having difficulty changing the browser tab title of my site and come here seeking some expert advice!

My first stop was obviously Settings > General > Site Title. That changes it correctly in my Dashboard title but only myself and the others I have working on the site see that behind-the-scenes area. The “browser tab title” shown to the public is what I really need changed.

In the Site Title box I currently have my new text “Halo 5 Universe | The Halo 5: Guardians News Site” but visiting my page “http://halo5universe.com” visitors see the old title “The Halo 5, Halo 4 and Halo 2 Anniversary News Site.” Unfortunately the old site owner changed it to this about 8 months ago and he can’t remember where he set it but said he remembered having difficulty.

As I read elsewhere, I looked in my Header.php but didn’t see the title there (old or new) to change manually. There must be somewhere else I can look to update this right?!

Thanks for any help you can provide me!!