Change the shortcut for Inserting a New Equation in MS Word for Mac I am having trouble changing the shortcut to add a new equation in MS Word for Mac.

Currently, the shortcut is set to: Control + =

I want to change this to the new shortcut: Shift + E

As per my findings on the internet, the procedure to do so is:

Word >> Tools >> Customise Keyboard and then search the command am looking to add/delete shortcut for and then edit it.

So when I do this, I go to the Category of:  Insert >> InsertEquation

Now the problem is, neither do I see the existing shortcut which should appear in "Current Keys" text box as visible in the screenshot, nor can I add a new shortcut in the "Press new keyboard shortcut" textfield, visible in the same screenshot. (My new shortcut does not show up in the text field even when I press it, so the Assign button next to it is greyed out and can't be pressed) 

Help me solve this please
You could use the Keyboard to reassign
(i dont have my mac with me but this shows the idea)