Unfortunately MS Office won’t let you customize the toolbars, but only use a “quick access bar” at the top.

However, there is a most useful option now, to search for any command or function you need easily, using this little “Tell me what you want” search box in Office menus.

To reach this command search box whenever available, as in Word, you don’t have to use your mouse!

Just press Alt+Q and this little search box is immediately activated, letting you type the command you need or select a previously searched for and used command.
Enjoy!

Being yourself an author or student you will perhaps appreciate especially this feature, that the very structure of the book will teach you how to work. The book contains even chapters on how to prepare a document for professional publishers such as Amazon. Reading Steven Adams' Writing a book or thesis in Microsoft Word you are surprised realizing it makes you want to work -- to think, write, use Word and be creative!