Hi there, lolley.
Thanks for bringing your question forward here in the Community. I'd be glad to provide some info about adding class items to your invoices in QuickBooks Online.
Good new! Yes, you can add class items to your invoices. There are just a few steps to get this done. Here's how:
1. Click the Gear icon in the top right corner of QBO.
2. Select Account and Settings.
3. Choose the Advanced tab from the left menu.
4. Make sure Track classes is turned on in the Categories section and choose how you'd like for them to appear on transactions.
Once you've completed these steps, there will be a section on your invoices to select the class item. The following linked article provides additional info about tracking your transactions by class.
Please feel free to reach back out here if you have any other questions. Assistance is only a comment or post away.