I. To save chagnes to a STAAD input file

Either:

select the Save tool on the File ribbon tab

or
press <Ctrl+S>.

Tip: Select the Save As tool on the File ribbon tab to save the file with a different file name or in a different location.

If this is a newly create STAAD input file, you will be prompted to type a file name and select a location to save the file.
(Optional) Click Save if you are saving for the first time or saving as a new file.