I can help you fix the vendor negative balance, @cipgifts.

You can enter the vendor refund check as a Bank Deposit. You have the option to add funds to the COGS account. I'll show you how:

1. Click the Plus icon.
2. Choose Bank Deposit.
3. Select the Account and enter the date.
4. Go to the Add funds to this deposit section.
5. On the Receive From column, select the vendor name.
6. For the Account field, select the COGS account.
7. Enter the $10.00 amount.
8. Click Save and close.

After that, you can run the Profit and Loss report to confirm that the COGS account already reduce the $10.00 amount. 

1. On the left menu, click Reports.
2. On the search field, enter Profit and Loss.
3. Customize the report to your desire.
4. Verify the report details.
5. If you wish to save the report, click Save customization.

That should get you going today, @cipgifts. I'm still here to help you further if you have additional questions. Just drop a comment below.