Hello there, @grantmelton.

You can turn off the option to Automatically apply credits from the Account and Settings. Let me guide you how.

1. Click the Gear icon at the upper right corner.
2. Under Your Company, click Account and Settings.
3. Go to the Advanced tab in the left panel.
4. Select Automation and remove the checkmark for Automatically apply credits.
5. Click OK.
6. Hit Done.

In case you would want to learn more about applying credit memos manually, here's an article: Enter and apply a credit memo or delayed credit

Let me know if you need more assistance with this. Have a great day!