Hi @freedumz,
Could you please share a bit more about your app's configuration?
Further, could you please share a screneshot of this issue?
If your Dates are displayed within a Label control, please take a try to set the Text property of the Label control to following formula:
Text(ThisItem.Due_x0020_Date,"dd/mm/yyyy")
Note: On my side, the dates (Due Date) are displayed within a Label control of a Gallery control.
On your side, you should type following formula:
Text(YourDateColumnName,"dd/mm/yyyy")
If your Dates are displayed within a Date picker control, please take a try to set the Format property of the Date picker control to following formula:
"dd/mm/yyyy"

More details about the Text function in PowerApps, please check the following article:
Text function
Best regards,
Kris