How to Avoid "Untitled" clutter?

I suspect I'm just missing the "Rename" command somewhere, but particularly in Writer, I'm getting multiple "Untitled" documents cropping up, b/c after I "Save As" a new title, Writer creates the new doc, but leaves Untitled in the hopper.

I don't see "Rename" anywhere. Having the same problem in Spreadsheet.

Can anyone help? Thanks!