Hi Mehmet, thanks for your answer, I have some issues:
1) I don’t see the functions.php file in Appearance > Editor > functions.php, and I’ve edited the file with Notepad++. Do you know how can I have the functions.php file visible in the Appearance section?
2) I’ve added the parameter above to the functions.php and updated the button shortcode, but it don’t work and the link still opens on the same tab. Was the solution tested? I’m sure that I followed your instructions, so I was wondering if there’s some other code to add or some other things I have to do, or another way to get this solved.