Renaming by pasting the change into preview list does not seem to work. The change is shown for a single file even if all of them are checked. The change is lost as soon as "Apply" is clicked. Am I doing something wrong here?
Use Ctrl+Shift+V rather than Ctrl+V if you want to paste the same thing into each file.
Ctrl+C/V on their own allow you to copy and paste portions of each file into itself.