Invoice number for keeps repeating on different customer’s invoices - how do I stop this? I need invoice numbers but different ones for each invoice?

It's nice to have you here today, @damienobeirne-ho. I'm delighted to assist you today in preventing duplicate invoice numbers in QuickBooks Online (QBO).

When users manually create invoices in QBO, there's a risk of accidentally entering the same number for multiple transactions. However, we can prevent this from occurring again by activating a warning message when a duplicate invoice number is detected. Here's how:

1. Go to the Gear icon and select Account and Settings.
2. Go to the Advanced tab and click the pencil icon in the Other Preferences section.
3. Turn on Warn me when I enter a bill number that's already been used for that supplier.
4. Click Save, then Done.
   

For now, you'll want to correct the duplicate ones by opening the invoice and entering the correct number in the Invoice no. field. 

If you've followed the instructions mentioned earlier and you're still experiencing duplicate invoice numbers, we can take some troubleshooting measures to resolve the issue. Cases like this are sometimes caused by an excessive cache that is corrupted in the browser. First, log in to your account in a private window. Please refer to these keyboard shortcuts:

• For Google Chrome browser: Ctrl + Shift + N
• For Mozilla Firefox browser: Ctrl + Shift + P
• For Safari browser: Command + Shift + N

Once resolved, return to your original browser to clear its cache or switch to another compatible one. It could be a short-term issue with QBO or the window you're currently using. 

When you receive payment from a customer, make sure to record it in QBO to mark the invoice as paid. Failure to do so will result in the invoice remaining open and unpaid in your reports.

Feel free to reach out anytime you have further inquiries regarding invoice numbers. The Community is accessible 24/7 to provide assistance. Stay safe, and have a wonderful day!