Sometimes you need to change the date format from the default US format (mm/dd/yyyy) to other, e.g. dd/mm/yyyy. Please follow these steps:
1. Go to Site Manager -> Development -> UI Cultures
2. Click 'New UI Culture' and insert for example following values:
UI culture name: British English
UI culture code: en-GB
3. Click OK to save changes.
4. Go to edit user (CMS Desk -> Administration -> Users -> edit the user account you are using) and change 'Preferred user interface culture' to British English (you can make the same setting in CMS Desk -> My desk -> My profile).
5. You may need sign out and sign in back for the changes to take effect.
You can also set this new culture as your default site culture from Site Manager -> Sites -> [Edit your site] -> General -> Default content culture.
Please note: the date format on the live site is changed according to the site culture.