What version of Shotcut are you using? When you open a project that is missing files, Shotcut will open a window to ask you to find those files. In your case, you could use that window to choose different files.
See an example here:
What version of Shotcut are you using? When you open a project that is missing files, Shotcut will open a window to ask you to find those files. In your case, you could use that window to choose different files.
See an example here: