新增：需要登录

app/controllers/api/v1/users/memos_controller.rb

@@ -1,5 +1,6 @@
 class Api::V1::Users::MemosController < Api::V1::BaseController
   before_action :load_observe_user
+  before_action :require_login
 
   def index
     @resident_expert = ResidentExpert.find_by(user_id: @observe_user.id)

app/views/api/v1/users/memos/_memo.json.jbuilder

@@ -7,7 +7,7 @@ json.forum_section_title memo.forum_section_title
 json.id memo.id
 json.is_fine memo.is_fine
 json.is_original memo.is_original
-json.memo_watched current_user.watched?(memo)
+json.memo_watched @current_user.watched?(memo)
 json.new_reply memo.new_reply
 json.praises_count memo.praises_count
 json.published_time memo.published_at.strftime("%Y-%m-%d %H:%M:%S")