This message in attached photo appear during booking the transaction ?? need clarification why

I'd be happy to clarify the message you received, esraa dabour.

The message means you missed assigning a class to your transaction. That's why QuickBooks is asking you if you want to save it without a class. You can select Yes, or choose No and then assign a class, and save the transaction.

You can actually change your settings to stop QuickBooks from warning you when you don't put a class to a transaction. Check out these steps:

1. Go to the Gear icon.
2. Choose Accounts and settings.
3. Select Advanced and click the Categories section.
4. Remove the checkmark in the Warn me when a transaction isn’t assigned a class box.
5. Click Save and then Done.

On the other hand, you may want to check out some class reports to see how each segment of your business is going. See more details in the Run reports by class article.

Let me know if you have more concerns about popups or anything in QBO. I'll be around to help. Take good care always!