Change confirmation message after submission

Dear support,

I want to change only confirmation message, can you please help me, I have tried following but not successfull

add_filter ('rwmb_frontend_after_form', 'emnsh_rwmb_frontend_before_display_confirmation');
function emnsh_rwmb_frontend_before_display_confirmation($config){
    $config['confirmation'] = 'Your lead has been successfully submitted. Thank you.';
    return $config;
}

and

add_action ('rwmb_frontend_after_process','emnsh_rwmb_frontend_after_process',10,2);
function emnsh_rwmb_frontend_after_process($config, $post_id){
         $config['confirmation'] = 'Your lead has been successfully submitted. Thank you.';
}

Thanks