The application can be customized using the Preferences, accessible from the GrandPerspective menu. The Preferences panel consists of three parts: Scanning, Display and Actions.

In the Scanning section you can configure the file size measure that is used to report file sizes. A change to this setting comes into effect when new folders are scanned. It does not affect existing views, or views that are created after re-scanning (as the latter take their settings from their original view). The file size measure that is used by a specific view window can be found in the Info tab. You can also select the unit system that is used to report file sizes. A change to this setting comes into effect immediately, and applies to all views. Finally, you can specify a filter that is used by default when scanning.

The Display section contains settings that affect the appearance of views. Here you can specify the color mapping and color palette that are used for newly created views. You can also specify if package contents should be shown for newly created views. Most of these settings only specify the initial appearance of newly created views. You can subsequently change a view's appearance from the Display tab. The display focus is an exception; it can be changed from the view's toolbar, when navigating the view.

In the Actions section you can configure whether file deletion is supported in the view window. You can disable deletion, enable deletion of single files, or enable deletion of entire folders. Furthermore, you can specify whether confirmation is required.

Beware: Deleting folders will move the entire folder to the Trash, including any files in the folder that are not shown in the view. A file may not be shown because it was masked or filtered, it could not be scanned because of insufficient permissions, or it appeared in the folder after the scan was made. In short, you should be very careful when deleting folders.

In the Actions section you can also specify whether or not the old view should automatically be closed when you rescan its contents. You can furthermore specify what should happen after you close the last view window. You can choose if the Welcome window should appear again, or if the application should terminate, or if neither should happen.