Hi there, @amy-yachtsalesin.

I'd be glad to share with you some insights about this feature you've mentioned.

Currently, there isn't a way to get the right cost per project made from one bill. To assign the correct cost, you can create a separate bill for each project. Then, by the time you're going to record your bill payments, you can split it to different projects in one go. To make sure that I've addressed your concern, I've replicated it by creating multiple projects and entering a bill. Here's what I've seen after that:

Also, you've mentioned that the bill was made last year, you can continue tracking it individually. Or if you still want to include and track it per project, you can re-enter the outstanding cost through a bill and assign it. But first, make sure that the previous bill cost has been cleared and edited like this:

Subtract the Paid amount of the Bill to the Total bill cost (TOTAL AMOUNT OF BILL - PAID AMOUNT)

Now, you can create a bill transaction in your Project and enter the outstanding cost of the previous bill. Then, add the exact date in the Memo field in every bill transaction that was dated last year. This is done so that it will be easier to locate it.

I've also added a screenshot to see how it looks like when paying multiple bills in one go.

For more information, you can check out this article: Enter and pay bills.

I've added this reference for your future task about assessing our business financials: Reconcile an account in QuickBooks Online. This contains tips on how to successfully finish reconciliation and how to troubleshoot it whenever there's something wrong during the process.

You can always tag my name in the comment section below if you need further assistance or if you have other questions. I'd be happy to guide you through. Take care always.