Footnotes without superscript references?

The other day, I created and exported a document as a Word .docx and my footnote numbers all appeared in the body within square brackets (like this [1]), with the footnotes gathered in a list at the end of the document.

This was great, but I wasn’t paying too much attention to what I was doing at the time and now I cannot for the life of me figure out how I did it.

When I go through (what I think is) the same process now, I just get the usual superscripted numbers in the body and corresponding footnotes at the end of each page.

Does anyone know what I might have done before (did I even insert ‘footnotes’?) and how I could do it again?