To save a temporary playlist with a different name
Click NowPlaying or MediaLibrary, click the playlist menu icon at the bottom of the Playlist pane or the Media Information pane respectively, and then click SaveAs.
-or-
On the File menu, click SavePlaylistAs.
Type the new name for the playlist, and then click Save.
Notes
If you have created a temporary playlist from an existing playlist, you can also save the playlist with the same name by clicking Save on the playlist menu or by clicking Save Playlist on the File menu,
By default, playlists are saved with a .wpl extension. You can also save playlists with the following extensions: .m3u, .asx, .wax, or .wvx.