I didn't clarify when I made the earlier comment, I was using an Android phone. In my phone, there's not a 'back' button per se. If you click the Android "back" on the screen, it takes you completely out of the book so that's a no-go in itself. In the Android Kindle app though, I noted with some books when you hop to the footnote (if it doesn't open as a popup in the page), there's a tiny little window below the footnote content, and if you click THAT, it'll go back to the original location. That's a pretty effective approach. However, I've noticed different experience with different books. Sometimes that little window doesn't appear either, and in that case, if I tap the little location slider where the button currently is, that seems to take you back to original. This is all a bit wonky how footnotes work 3 different ways across different books (these are THEIR books, not ones that I've messed with).