I don't see how to edit/change title of an existing document in Pages.
Command-click its name in the window's title bar, click on the folder enclosing it, close it, and change its name in the Finder.
You need to select the entire name and change it, part doesn't work (a bug).
when I did that the document disappeared and I cannot find it!
Choose Documents from the Finder's Go menu. If you previously saved it and didn't change its location, it'll be there.
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