Shouldn't the financial stuff (Principle etc) be part of the account class?
Another thing to do, is have a CBank class, which manages accounts & people, rather than have this in the person class.
IMO, the CPerson & CAccount classes, just store info related to these things respectively - like a record in a database. Then provide a minimal amount of functions to interact with these, but most of the work is done by the CBank class. That is create new accounts & people, find accounts, delete accounts etc.
You might also need a transaction class.
What I am saying is think about how things happen in the real world, to help design your classes. Class design can be quite tricky sometimes.
Here is some code I did to help someone else.
It is not complete & there is a red herring (forcing some thought on your part).
You will have to extend it a bit to have different types of accounts & transactions.
Hopefully this will give you a better idea of what goes in each class.