How to change Copyright in WordPress websites

Add this simple code snippet to change WordPress’s default copyright notice.

CODE SNIPPET in functions.php (after last line)

function create_copyright() {
$all_posts = get_posts( 'post_status=publish&order=ASC' );
$first_post = $all_posts[0];
$first_date = $first_post->post_date_gmt;
   _e( 'Copyright © ' );
   if ( substr( $first_date, 0, 4 ) == date( 'Y' ) ) {
      echo date( 'Y' );
   } else {
      echo substr( $first_date, 0, 4 ) . "-" . date( 'Y' );
   }
echo ' <strong>' . get_bloginfo( 'name' ) . '</strong> ';
_e( 'All rights reserved.' );
}