Please review Using Date Fields in Microsoft Word. You can use Alt+F9 to reveal the field codes. When you can see the field codes, you can modify them. you would want dd/MM/yyyy. Remember after you change it press F9 and Alt+F9 again to show field results.

There is no "updated" date. There is a SaveDate. It is seldom accurate in a saved document. It does not update until after the document is saved. When you reopen the document, if you update the field, it is accurate. Then, when you save the document with that updated, it is again out-of sync.

If it is in the footer, as with the filename field, it will update when you use print preview. It will also update if you select it and press F9.