How can I change the dvd region? The dvd info button is unclickable

Hi all,

I need to change the region code for a dvd, from #3 to #1.

I googled and tried pretty much everything, including the one on Apple Support. I opened the DVD Player app and tried to click 'dvd info' button, but it's unclickable. I tried to open the dvd first since media open button is clickable, but again, it said I can't open it because the media file is not available. (FYI, there is a mp4 and a pdf file in the dvd. Is that because of the pdf file?)

Is there any other way?

Or can anyone tell me how to make the dvd info button clickable?

Thanks,

Yoni