To update general account settings, go to Settings > General:
In General Settings you can:
Set local time zone and various formats (date, numbers, time display, and currency) for your organization
Set up Work time which entails Starting day of the week, Working days, and Man-day settings.
If a person does not have individual working days/hours set up (via cost rates), Work time will be used
Set the time rounding interval for Billable time
Edit default currency, payment terms, default markup on expenses, and number of decimal places shown