The general ledger report shows the transactions and total for each account in your chart of accounts. We're unable to customize this just to show the customer's entries.
What I can suggest is to pull up the customer statements in QuickBooks Online. This reflects the summary of their invoices, payments, credits, and balances.
Go to the Sales tab and select the Customers.
Choose a customer by checking the box beside their name.
Click on the drop-down arrow under Batch actions, then tap Create statements.