MS Word - switching to subscript and back

Is there any way to switch between regular text and subscript in Microsoft Word quickly? I can go to “format” then “font” then check the subscript box, but is there any way to do it faster (as when typing out chemical compounds)?

“Ctrl =” is sub
“Ctrl +” is super (so it’s really Ctrl,shift, =)
Do you know how to customize toolbars (It’s under “view; toolbars; customize”)?

There is a button for sub (or super) script that you can add too.

Thank you! I figured there was probably a toolbar customization, but I haven’t used Word since Word 97, and it has been a few years.