Time format can only be changed between 12h and 24h formats. It cannot be further customized.
To select between 12h and 24h formats:
Login to the Veloce Back-Office.
Start the Setup / Utilities module.
Click the System Config. link. (or use the Configuration > System Configuration menu item)
Click on the Misc. tab.
Locate the Military Format Time checkbox, at the bottom of the Options section.
Enable this option to select 24h format. Disable it to select 12h format.
There are no date format settings in Veloce. the date format used at the POS and in reports is determined by Windows regional settings of the PC where the Veloce Server is installed.