Why QB change my estimate templates without my consent? I don't what to use their new estimate template form.

Welcome to the Community, @zenen.

I understand the importance of your customized templates in QuickBooks Online (QBO) in line with your business.

Let me guide you on how to go back to the original custom estimates and make them your default.

1. Click the Gear Icon ⚙ at the upper right corner of your screen.
2. Select Custom Form Styles.
   
   
    
3. Once you’re on the Custom Form Style page, Choose your customized estimate, once you’re on the Custom Form Style page. 
4. Click the dropdown arrow beside Edit, then select Make Default.

Once done, you can use the customized estimates template you created for your up-and-coming transactions.

 You can check this article for more information if you encounter any difficulty with the abovementioned steps: Use and customize form templates.

Moreover, after customizing your estimates, you can check this article out if you want to visit and scan the transactions you have created: View sales transactions in QuickBooks Online.

Let me know if you have further questions about your estimates template in QBO. Just hit the Reply button and leave a comment below. I’ll jump right back to assist you.