my “places” lists only “my documents”
The save dialog opens by default on the directory defined in Tools>Options, LibreOffice>Paths, “My documents” item. When saving an already existing file, File>Save as opens on the file’s directory.
Adding new “locations” in the user profile doesn’t really make sense because the dialog will open on a single location. You can eventually change the factory default if you are not satisfied with it.
Several preferred “locations” can be preset in the dialog so that one can be selected by a simple click but this doesn’t depend on LO. It is an OS feature. And since you have provided no information about your computer (OS name, LO version, widget manager or desktop manager), you’ll receive no help about it because the way to configure these preferred list varies from OS+widget to OS+widget.
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