How to correctly record a mortgage that already started?

I just started using the app but I have a mortgage that I’ve been paying off for a year and a half already

If I input the interest rate, current remaining balance and monthly payment, it gives me a debt-free date that is 2 years too far in the future, I assume because the interest is calculated as of today and not as of 2021

Is there a way to fill the total amount, amount already paid, and start date so that the data is correct? This will also ensure that the capital in the expenses summary is correct

Thanks!

If you want to capture the earlier payments, I believe the only/easiest way to do so would be with a lump sum entry. You’d edit the start date and balance of the loan back to its true origination date, then add a single payment encompassing the principal and interest since then.
I can’t imagine why your payoff date isn’t calculated correctly though; it doesn’t seem as if the start date would make a difference. Do you pay bi-weekly but budget monthly? If so, Goodbudget wouldn’t be accounting for the extra payment each year maybe?