It is not possible to edit or change already generated screen saver (.scr or .exe files), but Ultra Screen Saver Maker projects (.ssp files) or Live Screensaver Creator projects (.lsc) only.

You should save a project file before you build the screensaver using the File/Save menu in Ultra Screen Saver Maker or Save button in Live Screensaver Creator, and you will be able to open it and change later on.

A screensaver project is a .ssp or .lsc file which contains settings and references to files necessary to create your screensaver again.