Why my Product currency A multiply by my home currentcy %0D%0A

Thanks for posting in the Community, @narai1685. 

When you turn on the multicurrency feature in QuickBooks Online (QBO), your home currency is set and remains unchanged. With this, the price in one Currency B for your products is based on the home currency. That's why your estimate amount doesn't match with your product price, but it exchanges with your home currency. For more details, see the After turning Multicurrency on section through this article: How Multicurrency Works.

I know how beneficial it is to get the same estimate amount to your product price, so I'll take note of your suggestion. This way, I can submit this to our product engineers. They can consider your feedback for future product updates.

I'd suggest visiting this website: QuickBooks Resource Center. Then, please scroll down the page and enter your Name and Email under the Help your business thrive, Sign up for our newsletter section. After that, click Submit so you'll get the latest news and product insights to your inbox. 

Once your customer accepts your estimate, you can convert it into an invoice. Just open the estimate from the Sales menu. Then, click Create invoice as seen in the screenshot below. For more details, check out this article: Convert An Estimate Into An Invoice. 

If you need further assistance, I'm always here to help. Have a great day, @narai1685.