The Localisation page can be accessed by going to the "Options" button from your main dashboard page. Click on "Account Settings":
And then by clicking on "Localisation":
Once on the page you will see the following options:
Date format - This lets you specify which format you would like all the dates to display in your account.
Timezone - This lets you specify which timezone you would like to use for your account.
Week Start Day - This lets you specify the week start day for your account. This updates the date pickers and calendar view to start on this day.
Working Days - This lets you specify which days are classed as working days for you. Days you don't choose will be greyed out in the calendar and scheduler views.