If you are using the cloud version, Ninox says it is dependent on the settings for your browser. If you have it set to English (United States) then it will set the date format as MM/DD/YYYY.

If you are using the app version, then it is set to MM/DD/YYYY.

To have fine control of your date fields, you will have to use a forumla field that uses format(fieldname, "DD/MM/YYYY"), or whatever you want it to be.

You can checkout: https://ninox.com/en/manual/calculations/reference-of-functions-and-language for all of the format options.

Do a search for "format(date" and it will take you to the right place on the very long page.