Do I need to keep the actual hardcopies of receipts after they are scanned into QuickBooks in case I am audited someday? Or is having them in this program enough?

Yes. We can keep a hardcopy of the receipt, junedvm-gmail-co.

This is to ensure accurate recording on both your QuickBooks Self-Employed account and the actual receipts. 

Also, if you want to attach a receipt to an existing transaction, you can check this reference: Attach receipts to existing transactions in QuickBooks.

Let me know if there's anything that I can help. Keep safe!