I insert the following simple code in the functions.php to edit the message in the footer dashboard "Thank you for creating with WordPress." but nothing changes. I have Version 4.9.8 Do you think this code is not effected in version 4 ?
// Admin footer modification
function remove_footer_admin () {
echo '<span id="footer-thankyou">Developed by <a href="https://www.example.com" target="_blank">www.example.com</a></span>';
}
add_filter('admin_footer_text', 'remove_footer_admin');
echo
out the result in a filter, that's not how filters work.