How do you change utc time on a digi tacho?

As previously said if more than 20 mins its a recal ,but when you say an hour out ,are the other maybe showing local time ■■?

If you scroll down to vehicle entry ok it then scroll to local time and ok it …It will display UTC on the left and local time on the right …You can change local in 30 min goes ,Obviously UTC is an hour behind uk time at the moment