I had mentioned this before - several years back - when I was using a Windows XP computer, now I'm using Win 10.
Sometimes - when I open a source template, the green Source Details portion of the Edit Source window does not appear. I just had an instance where I had to open the "Book Image Copy (Online)" template four times to finally get the Source Details section to appear.
Unfortunately, this problem is not limited to one single source template. It happens often enough that I just got tired of this problem and wanted to voice my frustration.
If this happens to a newbie, they would probably assume there was no Source Details section to the template they are trying to use.