A message from my Office 365 Tenant message Centre.
Feature Update: Modern experience of document libraries inside sites associated with Office 365 Groups
Published On : October 17, 2016
Expires On : December 16, 2016
Beginning October 24, we are changing the experience of document libraries in SharePoint Online sites associated with Office 365 Groups.
How does this affect me?
This change will be noticeable in two ways. First, we are changing the existing default document libraries (those named Shared Documents) inside group sites to use the modern experience unless the modern experience has been explicitly turned off previously inside those libraries. Second, we are changing the default setting for new sites associated with Office 365 Groups to use the modern experience.
What do I need to do to prepare for this change?
There is no action you need to take to prepare for this change. If you are not yet ready for this change, your library can be reverted to the classic experience by going to library settings and selecting “Classic experience” under “List Experience” in Advanced Settings, or by clicking “Back to Classic” in the lower left. Please click Additional Information to learn more.