[otrs] Format of "Age" in Customer Tickets to display only number of days

Hello how do I edit the format of the "Age" field in Customer tickets so it only displays the number of days (rather than hours, minutes,etc.) ?   Eg: at the moment the "Age" of a ticket shows "8 days 18 hours 24 minutes" - I want it to show "8 days".   Thanks a lot   Bis