I hope you're having an awesome week so far. Can you provide some further details on what's preventing you from creating an interest expense in QuickBooks Online? Any additional information or error messages you can provide will help to expedite the troubleshooting.
In the meantime, I recommend you check out these awesome guide on recording expenses:
With these resources and my help, I'm certain you'll have that interest expense recorded in no time. Please feel free to reach out to me here anytime you have questions or concerns, I'm determined to ensure your success. Thanks for coming to the Community and take care.