Cannot choose account category when invoicing and recording bills

Hi there, thiri-thaw-tiger.

Currently, there's no option to choose an account category when invoicing. That's the reason you're unable to select this on the invoice page. However, you can choose an account when you create a product and services that you use when you enter an invoice.

Here's how:

1. Click the Gear icon at the upper right corner. Then, select Products and services.
2. Choose the New button.
3. Select an item(Inventory, Non-inventory, or Service).
4. Add a name. If you track SKUs, enter a SKU for the product.
5. From the Category dropdown, select the category that best describes your product or service.
6. Select the I sell this product/service to my customers checkbox. If you don't sell the item, you can leave it unchecked.
7. From the Sales information section, enter a description.
8. Enter an amount in the Sales price/rate field or you can add the price when you fill out the invoice or sales receipt.
9. Select the Income account dropdown and the account you want to use to track the sale.
10. Enter the necessary fields. Then, hit Save and Close.

For additional information, you can click this article: Add product and service items to QuickBooks Online. This also provides steps on how you can delete an item.

It could be the Show Items table on expense and purchase forms option is turned off. Which is why you're unable to choose an account category when recording bills. I suggest turning on the said option from the Account and Settings page.

1. Click the Gear icon. Then, choose Account and Settings.
2. Go to the Expenses tab. Then, choose the Bills and expenses section.
3. Turn on the Show Items table on expense and purchase forms option.
4. Hit Save and Done.

Once done, you can go back to the Bill page and check if you already see the option to choose an account category under the Category details section. If still missing, I recommend clicking the Category details drop-down arrow to view the option.

Please check this article to see the definition of an invoice, sales receipt, bill, and statement so you can properly enter these transactions in QuickBooks Online: What is the difference between an invoice, sales receipt, bill, and statement.

Please know that you're always welcome to post if you have any other concerns. Wishing you and your business continued success.