Some of the template functions I use personally are right as a backup.

//修改logo的
function my_custom_login_logo() {
    echo '<style type="text/css">
   .login h1 a {
  background-image:url("http://tstrs.me/wp-content/uploads/2017/12/xcvfsdfs.png") !important;
        height: 512px; //修改为图片的高度
        width: 512px; //修改为图标的宽度
        -webkit-background-size: 512px; //修改为图标的宽度
        background-size: 512px; //修改为图标的宽度
   }
    </style>';
}
add_action('login_head', 'my_custom_login_logo');
add_filter('login_headerurl', create_function(false,"return get_bloginfo('url');"));
add_filter('login_headertitle', create_function(false,"return get_bloginfo('name');"));

//修改评论表单的
add_filter('comment_form_default_fields', 'unset_url_field');
function unset_url_field($fields){
    if(isset($fields['url']))
  unset($fields['url']);
  return $fields;
}

//以此身份登陆
add_filter('user_row_actions', function($actions, $user){
    $capability = (is_multisite())?'manage_site':'manage_options';
    if(current_user_can($capability)){
        $actions['login_as']    = 'ID", 'bulk-users').'">以此身份登陆';
    }
    return $actions;
}, 10, 2);

add_filter('handle_bulk_actions-users', function($sendback, $action, $user_ids){
    if($action == 'login_as'){
        wp_set_auth_cookie($user_ids, true);
        wp_set_current_user($user_ids);
    }
    return admin_url();
},10,3);

// 隐藏 姓，名 和 显示的名称，三个字段
add_action('show_user_profile','wpjam_edit_user_profile');
add_action('edit_user_profile','wpjam_edit_user_profile');
function wpjam_edit_user_profile($user){
    ?>
    <script>
    jQuery(document).ready(function($) {
        $('#first_name').parent().parent().hide();
        $('#last_name').parent().parent().hide();
        $('#display_name').parent().parent().hide();
        $('.show-admin-bar').hide();
    });
    </script>
<?php
}

//更新时候，强制设置显示名称为昵称
add_action('personal_options_update','wpjam_edit_user_profile_update');
add_action('edit_user_profile_update','wpjam_edit_user_profile_update');
function wpjam_edit_user_profile_update($user_id){
    if (!current_user_can('edit_user', $user_id))
        return false;

    $user = get_userdata($user_id);

    $_POST['nickname']      = ($_POST['nickname'])?:$user->user_login;
    $_POST['display_name']  = $_POST['nickname'];

    $_POST['first_name']    = '';
    $_POST['last_name']     = '';
}