I recommend that you forget using the Windows 10 Calendar app and that you install the FREE app "One Calendar" by One Spark (works with Google Calendar which is what I recommend) that your can easily find in the app store. This app shines above the calendar app that Windows 10 provides. It also is easier to use, looks way better and more. When using the One Calendar, calendar you will easily be able to add accounts and set them up so they "SYNC" automatically. Also, while in the One Calendar app you will see a Sync icon that you can click on when you wish and it right away, syncs all accounts. I encourage you and others here to try One Calendar! Free and if you don't like it, it easily uninstalls. As a heavy user of Google Calendar, I can tell you One Calendar is very good.