I'm glad that it worked now, @Mara.

Yes, you can record the processing fees under the Square fees expense account. There's no need to create a new one. If you'll want to edit the account, find it from the Chart of Accounts page, and select Edit from the Action column. 

Let's first run the Square Fees Account QuickReport to verify if you are able to save the transaction.

Here's how:

1. Go to Accounting and select Chart of Accounts.
2. In the Filter by name field, type in "Square Fees."
3. Select Run report from the Action column.
4. Modify the reporting period.
5. Click Run report.

Once done, it will show the amount of the processing fee. Otherwise, you'll need to recreate the transaction. You can follow the same steps provided by my colleague, katherinejoyceO.

I've got you here an article to learn more about common Chart of Accounts tasks: Understand the Chart of Accounts.

If you have other questions or concerns, please let me know in the comment section. I'll be here every step of the way. Have a good one.