好吧，我又来了。。哈哈，对不起。是的，我到处都在寻找答案，但是我使用的代码不同，我无法理解它。

所以我从GenerateWP.com 我再次请求帮助，但始终没有得到答复。这是：

class TP_Primo_Featured_Image_Options_Custom_Meta_Box {
    public function __construct() {
        if ( is_admin() ) {
            add_action(\'load-post.php\',array($this,\'init_metabox\'));
            add_action(\'load-post-new.php\',array($this,\'init_metabox\'));
        }
    }

    public function init_metabox() {
        add_action(\'add_meta_boxes\', array($this,\'add_metabox\'));
        add_action(\'save_post\', array($this,\'save_metabox\'), 10, 2 );
    }

    public function add_metabox() {
        add_meta_box(
            \'tp-primo-featured-image-options\',
            __( \'Featured Image Options\', \'tp-primo\' ),
            array( $this, \'render_metaboxrender_tp_primo_featured_image_options_metabox\' ),
            array( \'post\', \'page\' ),
            \'side\',
            \'default\'
        );
    }

    public function render_metaboxrender_tp_primo_featured_image_options_metabox( $post ) {

        // Retrieve an existing value from the database.
        $tp_primo_show_below_title = get_post_meta($post->ID,\'tp_primo_show_below_title\',true);
        $tp_primo_show_above_title = get_post_meta($post->ID,\'tp_primo_show_above_title\',true);
        $tp_primo_set_page_header = get_post_meta($post->ID,\'tp_primo_set_page_header\',true);
        $tp_primo_page_header_title_overlay = get_post_meta($post->ID, \'tp_primo_page_header_title_overlay\',true);
        $tp_primo_page_header_title_overlay_parallax = get_post_meta($post->ID,\'tp_primo_page_header_title_overlay_parallax\',true);
        $tp_primo_page_header_height = get_post_meta($post->ID, \'tp_primo_page_header_height\', true );

        // Set default values.
        if( empty( $tp_primo_show_below_title ) ) $tp_primo_show_below_title = \'checked\';
        if( empty( $tp_primo_page_header_height ) ) $tp_primo_page_header_height = \'\';

        // Form fields.
        echo \'<p><label><input type="checkbox" name="tp_primo_show_below_title" class="tp_primo_featured_image_locations_field" value="\' . $tp_primo_show_below_title . \'" \' . checked( $tp_primo_show_below_title, \'checked\', false ) . \'> \' . __( \'Show Below Title\', \'tp-primo\' ) . \'</label></p>\';
        echo \'<p><label><input type="checkbox" name="tp_primo_show_above_title" class="tp_primo_featured_image_locations_field" value="\' . $tp_primo_show_above_title . \'" \' . checked( $tp_primo_show_above_title, \'checked\', false ) . \'> \' . __( \'Show Above Title\', \'tp-primo\' ) . \'</label></p>\';
        echo \'<p><label><input type="checkbox" name="tp_primo_set_page_header" class="tp_primo_featured_image_locations_field" value="\' . $tp_primo_set_page_header . \'" \' . checked( $tp_primo_set_page_header, \'checked\', false ) . \'> \' . __( \'Set as Page Header\', \'tp-primo\' ) . \'</label></p>\';
        echo \'<p><label><input type="checkbox" name="tp_primo_page_header_title_overlay" class="tp_primo_featured_image_locations_field" value="\' . $tp_primo_page_header_title_overlay . \'" \' . checked( $tp_primo_page_header_title_overlay, \'checked\', false ) . \'> \' . __( \'Page Header: Title Overlay\', \'tp-primo\' ) . \'</label></p>\';
        echo \'<p><label><input type="checkbox" name="tp_primo_page_header_title_overlay_parallax" class="tp_primo_featured_image_locations_field" value="\' . $tp_primo_page_header_title_overlay_parallax . \'" \' . checked( $tp_primo_page_header_title_overlay_parallax, \'checked\', false ) . \'> \' . __( \'Page Header: Title Overlay/Parrallax\', \'tp-primo\' ) . \'</label></p>\';
        echo \'<label for="tp_primo_page_header_height" class="tp_primo_page_header_height_label">\' . __(\'Page Header Height\', \'tp-primo\' ) . \'</label>\';
        echo \'<input type="text" id="tp_primo_page_header_height" name="tp_primo_page_header_height" class="tp_primo_page_header_height_field" placeholder="\' . esc_attr__( \'\', \'tp-primo\' ) . \'" value="\' . esc_attr( $tp_primo_page_header_height ) . \'">\';
        echo \'<p class="fi description">\' . __( \'Use PX, %, REM, EM and VH based values.\', \'tp-primo\' ) . \'</p>\';
    }

    public function save_metabox( $post_id, $post ) {

        // Sanitize user input.
        $tp_primo_new_show_below_title = isset($_POST[\'tp_primo_show_below_title\']) ? \'checked\' : \'\';
        $tp_primo_new_show_above_title = isset($_POST[\'tp_primo_show_above_title\']) ? \'checked\' : \'\';
        $tp_primo_new_set_page_header = isset($_POST[\'tp_primo_set_page_header\']) ? \'checked\' : \'\';
        $tp_primo_new_page_header_title_overlay = isset($_POST[\'tp_primo_page_header_title_overlay\']) ? \'checked\' : \'\';
        $tp_primo_new_page_header_title_overlay_parallax = isset($_POST[ \'tp_primo_page_header_title_overlay_parallax\']) ? \'checked\' : \'\';
        $tp_primo_new_page_header_height = isset($_POST[\'tp_primo_page_header_height\' ] ) ? sanitize_text_field( $_POST[ \'tp_primo_page_header_height\' ] ) : \'\';

        // Update the meta field in the database.
        update_post_meta($post_id,\'tp_primo_show_below_title\',$tp_primo_new_show_below_title);
        update_post_meta($post_id,\'tp_primo_show_above_title\',$tp_primo_new_show_above_title);
        update_post_meta($post_id,\'tp_primo_set_page_header\',$tp_primo_new_set_page_header);
        update_post_meta($post_id,\'tp_primo_page_header_title_overlay\',$tp_primo_new_page_header_title_overlay);
        update_post_meta($post_id,\'tp_primo_page_header_title_overlay_parallax\',$tp_primo_new_page_header_title_overlay_parallax);
        update_post_meta( $post_id,\'tp_primo_page_header_height\',$tp_primo_new_page_header_height);
    }
}
new TP_Primo_Featured_Image_Options_Custom_Meta_Box;

"Show Below Title" 默认选中（这是我想要的…呜呜），但如果我取消选中并选中"Show Above Title" 点击显示的更新"Show Below Title" AND "Show Above Title" 已选中。。。呜呜！

我需要设置“在标题下显示”($tp_primo_show_below_title) 作为默认值。我似乎无法理解。我错过了什么？

非常感谢您的帮助。