Libraries let you view and arrange files stored in different locations. For more information, see Working with libraries.
You can change where a library gathers content from by including or removing folders in the library. To learn how, see Include folders in a library.
You can also customize the general behavior of a library by changing its default save location, or by changing the type of file that a library is optimized for.
A library's default save location determines where an item will be stored when it's copied, moved, or saved to the library.
Open the library you'd like to change.
In the library pane (above the file list), next to Includes, click Locations.
In the Library Locations dialog box, right-click a library location that's not currently the default save location, click Set as default save location, and then click OK.
Each library can be optimized for a certain file type (such as music or pictures). Optimizing a library for a certain file type changes the options that are available for arranging the files in that library.
Right-click the library you'd like to change, and then click Properties.
In the Optimize this library for list, click a file type, and then click OK.