Here we will discuss how to switch the default experience for list and libraries from new or classic SharePoint Online Office 365. In my previous post, I have already posted how to do the changes for site level classic view. Though you do the changes at site level still you will observe the Modern view for list and libraries. The modern view is amazing but it depends your requirement as well. If you have custom master page then you will have to revert classic mode.
Please find below steps to do the changes for list and libraries.
1. Navigate to list or libraries where you want to do the changes.
2. Click on List settings from top ribbon.
3. Click on advance settings.
4. Change the settings to classic experience and click on OK to save the changes.
Switch the default experience for list and libraries from new or classic SharePoint Online Office 365
Hope this will be helpful.