i have issues with the journal enteries serial numbers its generating automatic duplicates

Welcome to the Community, expert-ex818.

It's possible that when you create a journal entry (JE), QuickBooks generates a JE number that matches an existing one, and you saved it without being warned.

To prevent this, enable the Warn me if duplicate journal number is used option. You'll then be alerted to duplicates and can change the journal number before saving.

1. Click the Gear icon, then select Account and settings.
   
2. Choose the Advanced tab.
3. In the Other preferences section, toggle on Warn me if duplicate journal number is used.
4. Hit Save.
   

Should you have other concerns, feel free to leave a message.