Nice to have you in the Community space, @Sunny Accounting.
I see how important it is to maintain your accounts accurate in your QuickBooks Online (QBO) account. Altering a transaction can lead to discrepancies within your books. However, the option to lock a transaction in QBO is currently not available.
As a way around, you can change the user type of your QBO users. That way, they can’t view or alter your transaction. Let me show you how:
You can also read through Change what a user can do and see (user type) section this article for information about the process: Add, delete, or change user access.
Additionally, I encourage checking out our QuickBooks Blog page regularly. There, you’ll get to know what’s new in QuickBooks and what our Product team is currently working on.
In case you have other concerns in managing your transactions in QBO, don’t hesitate to tag me in your reply. I’ll be more than happy to work with you again. Have a jolly day ahead!