Lightning pages use tabs to organize data on the screen. By default the Activity and Details tabs are displayed. To better organize your data, you can reorder the tabs to work with keyboard commands or regular viewing.
To reorder tabs in Lightning Experience:
- Have a record open on the page you want to set the default tab.
- Click the Gear (Setup) button and choose Edit Page. Find the section that contains the tab headings and select it.
- Click and drag current tabs to the order you want in the Tabs section in the middle right of the screen.
- Click on Save and Activate to save the changes.
- Click on Back to return to Salesforce with the new default tab.
Follow the above steps on any page you want to change the tab Order.