This estimate number was already used. Try a different one to continue. Just ploease tell me how to change estimate number quickly

To change the estimate number, open the estimate and look for the Estimate number field. Just click into it and type the new number, then save.

If you want QuickBooks to generate numbers automatically without encountering errors, you can enable custom numbers. Here's how:

1. Click the Gear icon (⚙) in the top right.
2. Select Account and Settings.
3. Go to the Sales tab on the left.
4. Click the Sales form content section.
5. Turn Custom transaction numbers to On, then click Save.

For further guidance, check out this article: Customize invoices, estimates, and sales receipts in QuickBooks Online.

If you have any additional questions, please don’t hesitate to reach out. We're always here to assist you.