What if Quicken asks if I want to manually reconcile an account?

Changing a reconciled transaction affects future reconciliations. Quicken lets you know if you're about to change a reconciled transaction and asks you to confirm the change.

Your ability to change transactions after they are entered or even reconciled gives you complete control of your financial records. However, if you want to protect your data from accidental or unauthorized changes, Quicken lets you assign passwords to keep it secure.