Homepage Site subtitle is not displaying on tab/Facebook description

I am struggling to figure out support for this issue I have and I need help. Here is some basic site information:

Site Title: Pure Living 316
Site Subtitle: Powerful natural remedies for Cystic Fibrosis and Fibromyalgia
Site URL: http://pureliving316.com/
Theme: Colorway
Problem: WordPress SEO by Yoast

If you click on the URL in let’s say safari or chrome, it shows the tab saying:
New hope for Fibromyalgia, my journey into Young Living Essential Oils… – Pure Living 316

This is the latest blog post (Blog is split using categories on the site). However when I am on the homepage I want the tab to say the site title and the site subtitle.

Theme: I switched to the 2015 theme and it still does it.
Plugin: Turning off WordPress SEO fixes it, however I really would like to use that plugin for obvious reasons.

Please keep code modifications to a minimum and let me know what settings I need to change. I really don’t know much about CSS and don’t want to mess any of that up.

Thank you for any and all advice and support. I am still learning as I have not developed many sites. None of which I have had formal training to help.

~James