Hi, unfortunately this setting does not appear in Subclient Policies. If you have a list of the clients that you want to modify then you can create a batch script to modify this default 2 year deleted item retention.
Run the command below on the CommServe in the same location as the extracted zip to get the xml file above.
qoperation.exe -af change_endpoint_retention.xml -clientName CLIENTNAME_1_of_Many -fsSubClientProp/backupRetentionMode AFTER_DELETION_KEEP_ITEMS_INDEFINITELY -fsSubClientProp/afterDeletionKeepItemsForNDays -1
You'll need to qlogin.exe beforehand and qlogout.exe when you have finished.