The Save command will allow you to save the current layout to disk. If the layout you are working on already has been saved, selecting the Save command will automatically overwrite the existing layout. If you have not previously saved the layout, the Save As dialog box will be displayed and allow you to enter the filename as well as a description for that sign.

You should always Save a layout in our native .LW8 file format in addition to exporting, in case you want to edit the original file.