Here is [Amazon documentation on footnotes editing](https://kdp.amazon.com/en_US/help/topic/G201506450).

Here is how to *create footnotes in HTML*:

This is one of the simplest ways to create linked footnotes using HTML, but there are many others. Please note that Amazon requires footnote links to be superscript.

Place this HTML code in your main body content where you want the footnote link to appear:

```
<a id="footnote-1-ref" href="#footnote-1" epub:type="noteref"><sup>1</sup></a>   
```
Change the number value for each footnote that you include in your text. The first footnote in your book should use the number 1, the second footnote should use 2, the third should use 3, and so on:

And describe your footnote:

```
<p id="footnote-1" epub:type="footnote">Here is the footnote text</p>
```

After you've set all your footnotes, they'll be converted to endnotes automatically when you upload your book

Sometimes it will open as a popup, but sometimes the navigation will take you to the page. I don't know exactly why. It looks like there's some heuristics involved.

Try always to put your [footnotes in another section](http://www.jutoh.com/kb/html/section-0142.html) and have the link superscripted. You can find [more tips in this page](https://sketchytech.blogspot.com/2017/03/footnotes-for-all-one-footnote-format.html).