> If I open a PDF in Preview on my Mac and delete a page from it, it saves the change instantly. If I made a mistake, I can't just close it and re-open the orig

> If I open a PDF in Preview on my Mac and delete a page from it, it saves the change instantly. If I made a mistake, I can't just close it and re-open the original version. There's a system setting to (mostly) restore the old behavior: Desktop & Dock > Ask to keep changes when closing documents. Apple applications will still immediately update the file and disk, but it's a lot easier to discard all changes since the last save by closing without saving, and the on-disk file will be rolled back to the previous version. This setting has been around since 2012, I think one OS after they introduced the "auto-save" feature, and I've been using it ever since.