How do I keep track of interest paid on loans?

Hello there, @usercnypumps.

You'll first have to set up a liability account to record your loan and its payments. That should include the interest you've paid. Then, record your loan repayment by creating a check. From there, you'll have to select the expense account from the Category drop-down to record the interest accordingly. Let me guide you how.

1. Go to the + New button.
2. Select Check. 
3. Add a check number if you plan to send an actual check. If you use direct withdrawal or an ETF, enter Debit or ETF in the Check # field.
4. On the Category details section, select the liability account for the loan from the Category drop-down. Then, enter the payment amount.
5. On the second line, select the expense account for the interest and enter the amount.
6. On additional lines, add any additional fees (optional).
7. Select Save and close.

For the detailed steps, you can also refer to this article: Set up a loan in QuickBooks Online.

Additionally, you can also pull up the Transaction Detail by Account report. This way, you're able to monitor your expenses and manage them accordingly. Just go to the For my accountant section from the Reports menu's Standard tab.

I'm also adding this article to effectively manage your business transactions in QBO: Help Articles. It includes topics about banking, expenses and vendors, and reports to name a few.

You're always welcome to comment below if you have other concerns about managing your expenses and vendor transactions in QBO. I'm just around to help. Take care always.