In WordPress 4.7 these 2 buttons were removed. Incase you want them back on your editor, surely you can do it easily
Install This plugin. Activate it.
Go to Settings > Writing page. Here we can configure the settings of the plugin.
The plugin settings label is “Editor style”
It has a drop down with 2 options:
Drop down option 1: Simply to add these 2 buttons, selecting this option will add the buttons in the second row.
Drop down option 2: Re add buttons, selecting this option will add the buttons in the same place as they were before WordPress 4.7
Save the changes.
Done. GO and check out the post editor and use the Underline and Justify text button as before.
Happy WordPressing… 🙂