Quick Access Toolbar in Word 2010 allows users to add set of commands that would help them while working in Word. It is advisable to add the most frequently used commands as part of your Quick Access Toolbar. The Quick Access Toolbar by default appears at the top of the Word application i.e above Office Ribbon.
If you want to move Quick Access Toolbar below the Office Ribbon then you can do the following
Click the down arrow available on the QAT and select Show Below the Ribbon option from the menu list.
This would change the position of QAT and it would now appear below the Office Ribbon as shown below.
Similarly if you revert the changes and move QAT to the original position then again click on the down arrow and select Show Above the Ribbon from the displayed menu list.
If you have customized Quick Access Toolbar with all your desired commands and use them very often then moving it below the Office Ribbon might make your life easier in accessing these Commands.