Fixing Credit Card mistakes

A few days ago, someone answered some questions which was immensely helpful.  I'm hoping to have the same success one more time.  

The issue that was resolved was that I had 2 credit cards that I had setup improperly in QB. I had one set as the Primary and one as the Secondary. I corrected this by creating a third item in the chart of accounts and listed it as a Primary credit card, and then set the two actual credit cards as Secondary to it.

After doing this the charges and credits (payments) flowed into the Primary card and each credit card maintained the charges and payments specific to that card. Now that it has been corrected, I've discovered that having it this way for a few years caused some of my charges and payments to flow to the wrong cards. With the way it is now, one card register indicates it has a balance of -$658.52 and the other card has indicates a balance of $658.52. In other words, one card register balance is negative and the other is positive in the exact same amounts.

Since these two registers span multiple years, and assuming no new charges or payments, what is the proper way to correct this so I can reconcile all my accounts to zero? My accountant said it can be done with a journal entry, OR I can make the card that had the overage pay the card that is short.

I don't know how to do either of these suggestions so I'm reaching out to the community to see if both of her ideas are correct and if so, which is the better way, and how to implement.

I appreciate any help.