I can share some information about billable expenses added to your invoices, @TerriSR

For billable expenses, you must use an account of one of the following account types: expense, other expense, other current liabilities, other current assets, other assets, fixed assets, or COGS.

Updating the account of your billable expense won't affect your invoices. You can go to the Products and Services to update the income account of the item.

Here's how:

1. Go to Sales and select Product and Services.
2. Look for the product or service item and click Edit.
3. In the Income account section, choose the correct account.
4. Click Save and close.

In case you want to apply these changes to all of your recent transactions, simply mark the checkbox in the Also update this account in historical transactions when updating your income account.

For more details about this process, please see this article: Change the account for a product/service item.

Once you've received customer payments, follow this article on how to record them: Record invoice payments in QuickBooks Online.

Keep me posted if you have any other concerns about changing the accounts of your expenses and invoices. I'm always here to help. Have a great day ahead.