I've searched what seems like the entire Microsoft Online site and am having
difficulty finding an answer to what I think you be a very elementary
question - how do I insert a form field in Excel?

I've successfully created form fields in forms in Word so I get the basic
idea of how they work. My problem is, when I am working on the Excel sheet
I'd like to insert form fields in, on the forms toolbar, the form field
option, the "ab" button is greyed out. I cannot figure out how to activate
it or why it is grey in the first place. I've been able to insert checkboxes
in Excel no problem so I'm very confused. Anyone with some advice in a
foolproof, step by step manner would be greatly appreciated.