To customize the date format for displaying submission dates in the back-end for administrators, follow these steps:

1. Go to the Dashboard and click on the "Options" button in the toolbar to access the configuration page.
2. Modify the date format to your preference using PHP date formatting tokens. For example, you can use "F j, Y h:i:a" to display dates like "October 12, 2003 2:13 pm."
3. You can find a comprehensive list of PHP date formats by visiting the link provided here.

This allows you to personalize the date display format according to your requirements.