### Preferences

> Allows the user to customize the appearance and behavior of the GUI . Please note: some preferences take effect immediately, while others require DS9 to be restarted. Changes to the preferences can be saved by selecting the `Save` button`.` Use the `Clear Preferences` button to restore default settings.

> User preferences are stored in `.ds9.prf`. DO NOT EDIT this file, since it will be deleted or overwritten by DS9. At startup time, DS9 will search for a preferences file in the following directories, in order, `./, $HOME, /usr/local/lib, /opt/local/lib`.

> Users may have several different preference files. DS9 looks for a preference file with its own name. By default, if the application is named `ds9`, it will look for `.ds9.prf.` However, if the DS9 application is named `foo`, then DS9 will look for `.foo.prf.` In this manner, the user can have several predefined preference files that are activated by invoking DS9 with a different application names.