Hi there, @userart.

I'd be happy to help you with how to configure the date format in your QuickBooks Online account.
 

You can change it in the Settings, I'll show you how to do that, please refer to the steps below:

1. Go to the Settings and select Account and settings.
2. In the Advanced tab, select the Edit or Pencil icon beside the Other preferences section.
3. Click on the drop-down arrow beside Date format.
4. Choose the format that you'd like to show, dd/MM/yyyy in your case.
5. Select Save and Done.

I'll show you some screenshot to see how it looks like:

I've added an article for your future task in case you want to personalize your sales forms: Customise invoices, estimates, and sales receipts in QuickBooks Online.

You're always welcome to tag my name in the comment section if you have other questions. I'd be happy to answer them for you. Take care.