I have the information you need regarding the drop-down list under the description for products and services, bbhconstruction. I'll be pleased to discuss this matter for clarification.
In QuickBooks Online, there will be no drop-down list under the description for products and services when creating business transactions. The field is populated automatically by the information entered when setting up the item. You can also enter a description right on the form when needed.
Here's how the description field will look like on your transactions:

On the other hand, you might want to scan these materials for guidance on entering invoice and bill payments:
I'm more than willing to help with any inquiries you have when managing your products and services in QuickBooks Online. Inform me by clicking the Reply button below or post in the Community forum again.