The renamed (99KB) file from the old computer is already there. Can't I just delete this new, smaller (4KB) file, the one without the extension?
Are you sure it's the 4KB file which doesn't have an extension? Are you sure it's not the contrary? Because if it was the contrary, you'd just have to delete the 4KB file then add the extension to your 99KB file. But if it's like you say, then I really don't understand how it's even possible...
I checked the properties of the file & it IS a .cool file.
Sorry, you got me lost... How could it be a .cool file if it doesn't have an extension? There's no way unless Windows Explorer hides the extensions... But you say that the other file does have an extension... I'm lost
Could you please show me a screenshot of your file explorer.