No option in calendar to define none-working days

No option in calendar to define none-working days

The calendar does not have an option to define none-working days. In some conutires, the week day starts on Sunday, not Monday.
Additionally, the calendar does not account for none working days so if a task duration is defined as 4 days and starts on Thursday, the weekend days will be counted as working days and the task end date will be calculated as Sunday instead of the following Tuesday
Eidan Apelbaum