I'm here to help fix the issue you're having with invoice numbers in QuickBooks Online (QBO).
The sequence of your invoice numbers can be influenced by several factors. To start, let's ensure that the Custom transaction numbers feature is activated. Enabling this option will allow you to input invoice numbers in any desired number or letter format.
Here's how:
In QBO, go to the Gear (settings) icon at the top right.
Select Account and Settings.
Click Sales, then press on anywhere within the Sales form content section.
Make sure that the box next to Custom transaction numbers is not checked.
Hit on Save and then Done.
If it is enabled, please check the Audit Log to verify if any accidental changes were made. This will help determine if any modifications were made that could have affected the sequence of your invoice numbers. Refer to this article for further guidance: Use the audit log in QuickBooks Online.
If there are no changes, sign in to your QBO using a private browser (incognito). This will help us check if the browser is already full of frequently accessed page resources (cache and cookies) causing this unusual response.
Here's how:
Press Ctrl + Shift + N (Google Chrome).
Ctrl + Shift + P (Firefox).
Control + Option + P (Safari).
Ctrl + Shift + P (Microsoft Edge)
Once logged in, double-check the invoices. If everything looks good, return to your default browser and perform a clear cache to refresh the system. However, if the issue persists, try using other supported browsers.
To learn more about managing invoice numbers in QBO, refer to these articles for future reference: