Let me share some insights about your concerns when transferring credit card processing fees from COGS to expense in QuickBooks Online Accountant, @Charm25.

When transferring the credit card processing fee, changes you make will not affect the transaction records for the closed period. It will only impact the current and future periods. 

You can set up a new expense account for merchant fees and use it as a Category when recording the fee. Here's how:

1. Go to Settings ⚙ and select Chart of Accounts.
2. Click New. Depending on your account view, you'll see a panel labeled New account or New category. Select the option you see below for the next steps.
   
   
    
3. Press Save once done.

Also, I recommend reaching out to your 3rd party payment processor to find out how to do the mapping. 

Moreover, this change may affect your financial statements and tax filings, so it's always a good idea to consult with an accountant or financial advisor before making the transfer or any significant changes to your accounts. If you're not affiliated with an accountant, we can help you find one through this link: Find a ProAdvisor.

You may want to visit these handy articles for future reference to learn more about managing customer payments and personalizing sales forms:

• Customize invoices, estimates, and sales receipts in QuickBooks Online.
• Record invoice payments in QuickBooks Online.

Please get back here in this thread if you have any follow-ups about credit card fees. I'll be around ready to help whenever needed.