The users are confused because you have several rows that are exactly the same option.
They are scared because it is accompanied by a severe warning that "Once selected, it cannot be changed!".
As presented, it is impossible for the user to ensure that he is selecting the correct format, and it is impossible to correct it later.
Try match a more familiar sample date with formatting annotations Every date you are using. Do not use the incredibly ambiguous March 5, 0005 as your example date.
Select your preferred short date format: (o) M/D/YYYY → 4/5/2017 ( ) M/D/YY → 4/5/17 ( ) MM/DD/YY → 04/05/17 ( ) MM/DD/YYYY → 04/05/2017 ( ) YY/MM/DD → 17/04/05 ( ) YYYY-MM-DD → 2017-04-05 ( ) DD-MMM-YY → 04-Apr-17
Finally, I would recommend doing everything possible to allow the user to change this later.
For a real-world example, here is the date format selector in Windows 10: