MacOS automatically saves changes when closing TextEdit

Question

If I don't intentionally save a document in TextEdit, I expect it to be left as is. That is, I expect a changed document to prompt "Do you want to save?" so that I can choose Delete. This means you can accidentally save an unwanted version of a file.

I fixed this on my Mac when the "feature" initially became available, then something recently (April 2018) changed the setting back. See my answer below for the setting needed.

I'm writing this question because the answer to a similar question in OS X Lion is no longer current. Can I disable OS X Lion Autosave and Versions? Can I disable OS X Lion Autosave and Versions?

Answer 1

In MacOS 10.13, there's a setting in System Preferences->General called "Ask to keep changes when saving documents". It should be checked if you want to be prompted. a Modern MacOS just keeps the changes by default, creating previous versions accessible using the File->Revert To menu.