Why are sub cusomers not marked as paid when customer invoice is paid?

You'll have to make sure to tick mark the Bill parent customer option, Amanda. That way, the payment will reflect both on the parent and sub-customer. 

In QuickBooks Online, once the customer pays an invoice that is linked to sub-customers, both the sub-customer's and parent customer's invoice will be marked as paid and closed as long as you mark check the Bill parent customer option in the customer profile.

Let's go ahead and check the settings of your customer to verify whether the Bill parent customer option is selected. Here are the steps to follow in order to check this setting:

1. Go to the Sales tab and select Customers.
2. Click on the sub-customer's name. Select the Edit button.
3. Under Is a Sub-Customer, mark check the Bill parent customer.
4. Select Save.

For more detailed information about the option of using the Bill parent customer feature on invoices in QuickBooks Online. Refer to the following link: Use the Bill with parent option on invoices in QuickBooks Online. This article provides step-by-step instructions on how to create a delayed charge and add it to an invoice. 

If the issue persists after ensuring that you have selected the Bill parent customer option, I suggest accessing your QBO account using an Incognito/Private browser window to further investigate if the problem is specific to your browser.

You can use the shortcut keys below:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P
• Microsoft Edge: press Ctrl + Shift + N
• Safari: press Command + Shift +N

Once everything looks good, I recommend clearing your browser cache. This will help ensure that any temporary data or stored information that may be causing issues is removed, allowing for a smoother browsing experience. Otherwise, you can utilize an alternate supported browser or device. This is to have the best and most secure experience with QuickBooks Online. 

In case you're interested in enhancing your sales forms with branding, managing customer payments, or exploring other sales-related activities, I encourage you to access each of the following resources for detailed guidance:

• Receive and process payments in QuickBooks Online with QuickBooks Payments
• Customize invoices, estimates, and sales receipts in QuickBooks Online
• Sales and customers

Please don't hesitate to contact us if you have any further concerns or questions about invoices and customers. The Community is always here and ready to provide you with additional assistance and support. Have a great day.