why aren't my changes to accounts and settings saving?

Let me help you connect to the appropriate support, pureflectionpc.

First off, since the issue persist when trying to change your company address in QuickBooks Online. I highly suggest contacting our QuickBooks Online Support team to resolve this efficiently.

Here's how to connect with them:

1. Click the Help menu.
2. In the pop-up panel, go to the Search tab.
3. Hit the Contact Us button.
4. From the text box, type in your concern.
5. Click Chat with us.

When reaching them, please make sure to know the availability hours to make sure your concern will be getting in touch: Get help with QuickBooks products and services.

For concern about keep receiving cc'd emails of customer invoices. Let's ensure when creating transactions we need to clear the cc/bcc field.

Please refer to the screenshot below:

Moreover, here's an article for future reference: Receive and process payments in QuickBooks Online.

The Community team is always here if you need anything else.