In QuickBooks Online (QBO), the invoice will keep consolidating when you choose the Group time by service. To avoid this, you can choose Don't group time to show the single time entry of your invoice.
Here's how:
On the invoice creation screen, select the customer with a pending time activity under Customer.
From the Add to invoice window, choose Don't group time.
Click Save and close once done.
Be sure to show the service when entering the time if you haven't done so already. On the weekly or single timesheet screen, click the Gear icon then check Show service. This will let you assign a specific service to your entries.
I'd also suggest editing your time entries if you haven't added service for them yet. Simply go to Sales, select a specific customer, then open the Time Charge transactions.
You might also want to check our articles for guides. They also contain information on what else you can do in QuickBooks Online.