I can share some information about editing your transactions in QuickBooks Online (QBO), @JDetamore20.
Editing your prior transactions and adding a class won't cause any problems with your past data. You have the option to assign one class to an entire invoice, receipt, or any other customer transaction. You can refer to this article for detailed guidance on locating and editing a transaction: Find, review, and edit transactions in account registers in QuickBooks Online.
From here, you can run sales, expenses, profitability, and other reports by class. See this article for detailed guidance: Run reports by class. For detailed guidance on how to apply filters to get the information that you need: Customize reports in QuickBooks Online.
Let me know in the Reply section if you need further help to edit your transactions. I'm always here to help. Have a great rest of the day!
