How to put PDF file into main file directory with nice name?

I have downloaded the PDF file of an existing entry and I want to add it to the entry.

If I drag the file from my directory and drop it on the entry, the file is moved to the main file directory and renamed as per the file format pattern. Good. But is there a simpler way?

If I push the + near the “file” field, the file is not moved and the path to the original file is put in the entry.
If I then push “Copy linked file to folder…” the file is copied to the main file directory but not renamed.
What should I do?

P.S.: I’m on windows with the latest development version of JabRef

To rename automatically PDF files using the key pattern, you can use the Cleanup entries menu (under Quality) and then select the checkbox “Rename PDFs to given filename format pattern”.

Alternatively, right click:

Any idea why the item “Rename file to defined pattern” is grayed out?

I found the answer: active only if the file does not follow the defined pattern!

That is greyed out when the file is already in the directory and named according to the pattern. This was just a random file I picked