Hello there, namhla,
In QuickBooks Online (QBO,) account numbers are manually entered. Let me show you how it's done.
You need to enable the option and manually allocate for each account in your Chart of Accounts by following the steps below.
To enable, here's how:
Once done, you're now ready to allocate one to your accounts. Here's how:
Should you have other questions about QuickBooks features, let me know by leaving a comment. I'm just around if you need help.