Drupal MD Alpine theme: How to increase the length of the title and description field of the Parallax

/sites/all/themes/md_alpine/inc

    $form['md_alpine_settings']['design']['design_parallax']['parallax_'.$i.'']['pr_'.$i.'_title'] = array(
        '#type' => 'textarea',
        '#title' => 'Parallax '.$i.' Title',
        '#default_value'    => theme_get_setting('pr_'.$i.'_title') ? theme_get_setting('pr_'.$i.'_title') : '',
        '#max_length'   => 1000,
    );
    $form['md_alpine_settings']['design']['design_parallax']['parallax_'.$i.'']['pr_'.$i.'_des'] = array(
        '#type' => 'textarea',
        '#title' => 'Parallax '.$i.' Description',
        '#max_length'   => 1000,
        '#default_value'    => theme_get_setting('pr_'.$i.'_des') ? theme_get_setting('pr_'.$i.'_des') : ''
    );