I would like to customise statements with custom fields or using data inputting with a customer data record to appear in a statement

It's great to have that feature added, Umesh. For now, I encourage you to communicate directly with our Product Development team using the 'Send Feedback Online' option in your QuickBooks Online account. 

To submit your feedback, you can follow these steps:

1. Go to the Gear icon. 
2. Select the Feedback option.
3. Enter your product suggestion.
4. Click Send.
   
   

For future reference, you can check this article to personalise and add specific information to your sales forms: Customise invoices, estimates, and sales receipts in QuickBooks.

If you need further assistance with managing your sales forms, just click the Reply button. I'm always here to help.