Cannot show copyright at the footer

or redefine the backlink by this in your child-theme functions.php:

/**  new backlink in copyright insertion*/
function new_nolink(){
$kriesi_at_backlink = " - <a href='https://your-link'>your link text</a>";
return $kriesi_at_backlink;
}
add_filter("kriesi_backlink","new_nolink");

Of course, you then had to remove the [nolink] from the copyright input field.

_____________

different way to write:

function my_own_backlink($link){
  $no = "rel='nofollow'";
  $target = "_blank";
  $backlink_url = 'Backlink URL';
  $theme_string = 'Custom Backlink Text'; 
  $link = " - <a {$no} href='{$backlink_url}' target='{$target}'>{$theme_string}</a>";
  return $link;
}
add_filter( 'kriesi_backlink', 'my_own_backlink', 10, 1);