As far as I know, this dropdown list is not customizable. Maybe someone else can chime in on this, but it seems like something I would have heard about if it were able to be customized.
If you selected the shortest time frame in the list, the reports should appear with the most recent at the top of the list. That would give you the view of today or this week. Today's reports may still show as processing as the payment status which would also help identify ones you are looking for.