Office 365 – SharePoint is ever evolving. As a part of this evolution, new experiences are rolled out to Office 365 SharePoint on a regular basis. As an admin of the organization, this can sometime be painful when supporting non-technical users. Office 365 team recently released an update to the default experience for lists and libraries. As an admin, you may want to switch your SharePoint farm to continue using the classic (old) experience to ensure your end users don’t see this change. Below are steps that you as an administrator will follow to keep your Office 365 SharePoint in the classic experience.
In your Office 365 tenant Admin, Choose Admin centers and then SharePoint.Choose Settings. Next to SharePoint Lists and Libraries experience, select Classic experience.
NOTE: Keep in mind that users can change the experience in specific libraries or sites back to new if they choose. A change to settings at the library and list level overrides changes at the site, site collection, and tenant level.