If your goal is to make eBook(s), leave Word out of the equation. Use a good text editor like Notepad++. Type in your text, with text markup... _italic_ *bold* put in notes where images go and and where you want the text centered, blockquoted and other styles.
In Notepad++ you can so easily surround each paragraph with <p></p> using search/replace and you can easily but in the code for bold and italics using regex. to replace the _italic_ and *bold*
You can just add the classes to each part of the <p>,</p> you need. replace the <p></p> in the headers for <h2</h2> as needed. It's actually a lot easier to do then it is to clean up the mess you get in Word. Also, if you want, just make a copy of the file, load it into Word, use the spell checker and any errors found, also fix in the text file.
Notepad++ uses tabs so you can have each chapter a separate file. Then when ready, use Sigil to build the ePub from your set of separate text files. It's not hard.
Once you learn to do this, you'll wonder why you ever bothered with Word.