Hi,

Open Admin console.
Select master server from left under host properties.
Right click -> properties
On the new window, select Retension period

This is the place to view and change the retension levels.

If none of the default rention periods suit you can amend them to any multiple of hours/days/weeks/months/years or infinite (i.e. 'never' expire) or expire immediately as directed by Scorpy but check the 'Impact Record' to see how changing an in use retention period would affect any current images.