为了保持提交的值，需要将其保存到相应的选项数组中。为此，可以添加另一个函数(pe_save_settings() 在本例中）捕获表单提交并保存字段内容。以下是完整的工作代码：

<?php
/*
Plugin Name: Test option page
Text Domain: test-option-page
*/

function reg_settings(){
    register_setting(\'pe_theme_options\',\'pe_theme_options_item\');
    add_settings_section(\'pe_main_settings\',\'Main Settings\', \'\', __FILE__);
    add_settings_field(\'pe_bannar_heading\', \'Bannar Heading:\', \'pe_bannar_heading_setting\', __FILE__, \'pe_main_settings\');
}

add_action(\'admin_init\',\'reg_settings\');

function pe_bannar_heading_setting() { 
    $options = get_option(\'pe_theme_options_array\'); ?>
    <input id="pe_theme_options_item" name="pe_theme_options_item" type="text" value="<?php if ( isset( $options[\'pe_bannar_heading\'] ) ) { echo $options[\'pe_bannar_heading\']; } ?>"/>
    <?php 
}

function pe_add_menu_page(){
    add_options_page(\'Theme Options\', \'Theme Options\', \'administrator\', __FILE__ , \'display_options_page\');
}

add_action(\'admin_menu\',\'pe_add_menu_page\');

function display_options_page() {
    $options = get_option(\'pe_theme_options_array\');?>
    <div class="wrap">
        <h2>Yellow Blog Options</h2>
        <form action="options.php" method="post" enctype="multipart/form-data">
            <?php 
            settings_fields(\'pe_theme_options\');
            do_settings_sections(__FILE__);
            submit_button( \'Save Settings\', \'primary\', \'pe_new_option\' );
            ?>
        </form>
    </div>  
<?php }

add_action( \'admin_init\', \'pe_save_settings\' );

function pe_save_settings() {
    if ( isset( $_POST[\'pe_new_option\'] ) ) {
        $new_value = trim( $_POST[ \'pe_theme_options_item\'] );
        $options_array = get_option(\'pe_theme_options_array\');
        $options_array[\'pe_bannar_heading\'] = $new_value;
        update_option( \'pe_theme_options_array\', $options_array );
    }
}