Change Magento Calendar date format

[rejoiner]

How to change in Magento date format for Calendar from mm / dd / yyyy to dd / mm / yyyy ?

I have tried change locale, nothing.

Also for Calendar.setup change setup setting ifFormat: "%Y-%m-%d",

All time same format.

[richiemcfarlane]

in admin go to System > Configuration > Catalog

Date format can be changed in Date & Time Custom Options

[rejoiner]

In admin panel was. And same issue with date format.