When running the Customer Balance Detail Report some receipts dated 2025 will be reflected in the report if their due date falls in 2025, Louise.
See the screenshot below for reference:

Since you need to reflect transactions only for 12.31.2024, we can edit the transactions if they have a due date for 2025. Here's how:
- Log in to your QBO account.
- Go to the Reports menu and enter the report name Customer Balance Detail Report.

- In the Report period field, select Custom dates and enter 2024-12-31 in the as of field.

- If there are transactions dated 2025 under the Due date column, click the specific date and edit to adjust.

- Once done, click Save.
Just the same process above when generating a Customer Balance Detail Report.
You can personalize your reports in QBO based on your preferences, check out this article: Customise reports in QuickBooks Online.
Please revisit this thread or click the reply button if you need further assistance in generating your customers report.