Need to manage multiple libraries in Sora. And the explore tab. Tap your school or library name in the upper left-hand corner to toggle between collections. 

You can also tap the three-line main menu to view all of your libraries, and switch between them at any time. 

Your current library will be indicated with a check mark. Tap edit. Select the red trashcan icon to delete any added library. Please note your school library has a star icon next to it and cannot be deleted.

By default, Once you add a library, your searches show results from all libraries simultaneously. Start with titles from your school's digital collection first, followed by titles from any public libraries you have added. 

You can change this default setting under the main menu.