Hello @marcum88,
Bank transactions can only be linked to the same transactions posted into the system. Thus, expenses can only be linked to an expense, a check, or a bill.
In addition, here's an article you can read to learn more about categorizing your bank transactions: Categorize and match online bank transactions in QuickBooks Online.
Lastly, I've got you this helpful article for ideas about how you can reconcile a bank account: Reconcile an account in QuickBooks Online.
If there's anything else that I can help you with, let me know in the comments. I'll be here to lend a hand.
