Hello,
It's essential that you're able to edit your invoice number so you can keep your sales forms in proper order. There's a setting in QuickBooks Online that makes this easy for you.
To turn on Custom transaction numbers, follow these steps:
1. Click the Gear icon
2. Select Account and Settings
3. Click Sales on the left menu bar
4. Under Sales form content, turn on the feature called Custom transaction numbers by clicking the small pencil icon on the right side
5. Click Done
Once this setting has been activated, you'll see a customization field on your invoice to edit the invoice number. You can simply make a manual adjustment to put the invoice number back in order.
If you have any questions about this, just let me know.
Have a good one.