I can share a bunch of info and steps to ensure you can assign classes to your Chart of Accounts list in QuickBooks Desktop (QBDT), @InterlakenGolf.

First off, you can assign classes to your income and expense accounts only. Also, this feature is available in QuickBooks Enterprise. For more insights, please review this resource: Set up and use class tracking in QuickBooks Desktop.

If you meet the above requirements and still unable to do it, I recommend updating your QuickBooks Desktop to the latest release. This is to ensure you have the latest features and needed patches.

Then, perform the steps given by my colleague again. If the issue persists, I recommend you run QuickBooks Tool Hub to identify and fix possible program or company file issue. For more details, please check out this article: Fix common problems and errors with the QuickBooks Tool Hub.

You can also pull up and customize class-related reports in QBDT. For more tips, please see this handy article: Filter, sort or total reports by Class.

I've got your back if you have more questions about managing your lists or reports in QBDT. Just tap the Reply button so I can assist you right away. Take care and stay safe always.