Word 2016 title display appears three black squares solution

Solution:

        1, move the cursor to the right of the black block, then pressing the left direction key of the keyboard, then block into dark gray, is "selected" state.

        2, then press the keyboard combination "Ctrl + Shift + S" following window will appear on the left side of your Word, then click on the box at "re-apply" button

After you are done, you will find that your three successful title appeared!