While launching an application for unauthenticated/Anonymous user, the idle tab for the Anon account might default back to 10 minutes even after manually setting it to some other value.

The following steps can be followed to test the behavior:

• From a VDA running 7.9 or higher, run the below .exe to create the Anon users:                                                    C:\ProgramFiles\Citrix\ICAConfigTool\CreateAnonymousUsersApp.exe
• Open 'Local Users and Groups' and view Anon000 account. On the Sessions tab change the 'Idle limit' to Never.
• Publish an app like Notepad to Unauthenticated users (Give access to unauthenticated (anonymous) users - Users Tab); no credentials are required to access Storefront).
• In the Storefront console, create a new store for unauthenticated users. Select the "Allow only unauthenticated (anonymous) users to access the store from the Store name tab"
• Launch the application.
• View the Anon user account again in the VDA console and the 'Idle limit' will be set back to 10 minutes. 
• This behavior does not happen in VDA's 7.8 and below.

• We have a registry which has the default idle timeout value captured. The value can be changed from the following location: HKLM\System\CurrentControlSet\Control\Citrix\AnonymousUserIdleTime.
• To set the idle timeout to 'Never' set the value in registry to 0.
• This registry can be changed to set the value of the Session Idle Time to the desired value.