I had create a custom form styles for my estimate & Invoice, but I dont know how to map it to my existing done Estimate

Let me share some information about the custom template, userhuilynnchua.

If you're referring to importing your custom estimate to QuickBooks Online (QBO), just access your DOCX template after designing your custom form style. Then, match your estimate fields with QuickBooks fields to upload it successfully. Here's how:

1. Open your DOCX template.
2. Identify text or fields that don’t change with each print as you design your template. Logos, company information, certifications, and such are static info. Make it part of your template.
3. Replace all fields with scalar or table fields, as appropriate to your chosen form type.
4. Make sure all fields match the EZ Map fields defined in the EZ Map catalogue.

Then, follow Step 2 until Step 4 in the Import custom form styles for invoices or estimates article to finish the process. You can also customize your estimates in QBO. 

Feel free to visit our Manage Customers and income page for more insight about managing your customer transactions.

I'd like to know how you get on after trying the steps, as I want to ensure this is resolved for you. Please reply to this post and I'll get back to you. Have a great day ahead.