Could I connect my bank account to receive world-wide payment online if I reside in Cambodia?

If the bank is supported, you can connect it, poeurt4u.

However, you can send a request support for your bank if it's not yet added. On the Connect an account page, click the Request support for your bank. Provide the bank's name and web address, then click Request.

If you're referring to receiving online payments, it's unavailable in your region. You can check out this article on how to record a customer payment: https://community.intuit.com/articles/1781149.

If you have additional questions about using QuickBooks, you can always post here in the Community.