Thank you for
reaching out on the community and telling us about your issue. I'm just wondering here, is the account manual entry or is it downloaded from the bank? Depending on method here will let us know if we're able to change transactions. Downloaded accounts do not let us change any information inside of the loan but manual accounts do let us adjust it. If it is a manual account go to the account that the transfer was made from and click on the transaction. Once clicked on you should be able to go to the split button and see how much is feeding directly into the account and adjust it. Also, look in the bills and income tab to see if it's potentially a reminder that hasn't been entered in the register yet if it is a manual loan.
I would also
recommend looking at our support article
here for more information regarding loans in quicken
Please let us know
if this helps resolve the issue for you.