I can convey some ideas for keeping the invoice sidebar menu from opening, Andrew134.

We're unable to disable the automatic opening of the Manage panel. This feature is designed to allow users to easily personalize invoices right from the creation stage. However, you can minimize the panel by clicking the X icon for a cleaner view while managing your invoices.

In addition, here's an article that covers on customize invoices in QuickBooks Online using the new invoicing layout: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Once you're ready to close your invoices, you need to track the customer's payment and link them to your invoices. Please refer to this page for the complete instructions: Record invoice payments in QuickBooks Online.

Let me know if you still have other concerns about the invoice preferences. I'll be around to help. Keep safe.