Date and time settings on Nokia N97 mini can be accessed using the menu button.
Select menu button on your mobile phone.
Select Settings menu
Select Phone menu
On selecting Date and time option, you can find various features related with Date and time functions.
If you want to change the time zone of your mobile phone, then you can use the Time zone field to set the required Time Zone.
And for example if you want to change alarm tone for your clock, then you can use the Clock alarm tone field to set the required tone.
Similarly if you want to change the date format on your phone, then you can use the Date format field to set the right format for your phone.