Hello mauramer,
I love that you're working with your client to help them manage their books. The Accountant's Copy of a QuickBooks Desktop company file is a great way to ensure that you're able to make the necessary changes and then have them applied to their file afterward. I know it's important to make sure each of those changes are received, and I have an article that can help you and your client troubleshoot.
Part of QuickBooks's goal is to provide comprehensive articles that can guide through the process of completing tasks in the program as well as troubleshooting if needed. There's an article here in Community called Resolve errors and unexpected results when importing accountant's changes, so I recommend starting there.
To get help with those steps, or if they don't resolve the issue, the QuickBooks Desktop support team is the next best resource. Take a look at the Intuit QuickBooks Desktop software support policies page to learn more about reaching support. At this time, all QuickBooks Desktop support is available from Monday to Friday between 9 a.m. and 8 p.m. ET due to reduced staffing, but I assure you we're still here to help!
Have a great rest of your day!