Manage Subtab Apps in Salesforce Classic

From Setup, in the Quick Find box, enter Apps, and then select Apps to show your org’s subtab apps.

You can do the following:

• To view details for a subtab app, click the name in the Subtab Apps section. This section displays the subtab app properties, such as which tabs are part of the app, including any tabs that aren’t yet deployed. To view details, click custom tabs in the Included Tabs list.
• To change the properties of a subtab app, click Edit to choose the tabs to include in the subtab app, change their display order, and set the Default Landing Tab.
  

  Note Administrators can change permission sets or profile settings to limit users’ access to each tab. This way, administrators can make specific tabs available to some users but not to others.