The latest version of WordPress which around the time of this post was 4.7.4 for some reason did away with the Fully Justify button and the Underline button on the TinyMCE Visual Post Editor. I am sure there are valid reasons for this, possibly due to a recently announced future update including elements surround the Post Editor in WordPress. But some users wanted these buttons back and so a very useful and very simple plugin was made by Daniele Alessandra called “TinyMCE Recover“.
All this plugin does is place the Fully Justify and Underline buttons back on the WordPress Post Editor Toolbar. Exactly what I needed. There really is a plugin for everything.