Easiest way to customize keyboard shortcuts

The usual method to customize the keyboard shortcuts in MS Office Word is to go to File --> Options --> Customize Ribbon --> Customize button after the label "Keyboard shortcuts:".Then one has to choose the category in which the command exists and then the command within the category!
See the Video below:

Look also into this article for details on this method

There is an easier and more intuitive way for doing the same.

1) Press Ctrl + Alt + the plus key on number pad.
     If you do not have an extra number pad, i.e. when you are working on a laptop: try to use the Fn key alsong with the "plus" key in the same color as the Fn key! 
If this did not work, find if the numlock is set or not and then try the Fn key once again.

2) If step 1) works, then you should see the loop squared symbol (⌘, U+2318) in place of the usual arrow point!
     This symbol is called by many names, but has the Unicode character called PLACE OF INTEREST SIGN, more here

3) Now, you can simply move the loop sqaured symbol freely to any button on the ribbon and click to open a customize window where you could define a new short cut to this command and then assign the newly defined shortcut!

$) Thats it!