Microsoft recently rolled out document library updates for some tenants in SharePoint Online. (Office 365). If you have not read about this then Ben have done a really good job providing all the details. You can read his blog here.
One thing to note this change is not rolled-out to everyone. It is just to the tenant who selected to participate in preview features.
So if you want to have these changes and any future updates rolled out to your tenant as soon they are available then you follow the steps below.
1) Go to your SharePoint Admin page.
2) On your SharePoint Admin page click Settings.
3) On the settings page scroll down and select Enable Preview Features under Preview Features section.
4) Click OK.
Now after you perform these steps it could take up-to 72 hours for changes to rolled out. So be patience and eventually you would see a message on your document library page about the changes.
I hope this helps someone.