1) how to change created ac number from 4000C00 to 4000C80? 2) how to open multiple window in QB? 3) how to customize ledger the filter to show individual account?

I can help you manage your accounts, suancomm-gmail-c.

Once you have created account numbers in your Chart of Accounts, you can set the list into ascending order based on the account numbers. Here's how to do that:

1. Go to the Accounting menu.
2. Select Chart of Accounts.
3. Click the NUMBER header to arrange it in ascending order. 

Now you have the list from 4000C00 to 4000C80. To open multiple windows in QuickBooks Online, just click the plus ( + ) button to open a new window tab. If there's a section you want to open in a new tab, just use the right-click of your mouse. Then, select Open link in a new tab. You can refer to the screenshot below for your reference. 

You can run the Account List report and customize it to uncheck account we want to exclude. I'll show you how:

1. Go to Accounting and select Chart of Accounts.
2. At the upper-right, click the Run report button.
3. In the Account List Report page, click Customize.
4. Select the Filter drop-down and check Account. 
5. From the Account drop-down, unselect the accounts you want to exclude. 
6. Customize the report further to the display you need and then click Run report.

I'll be adding articles that will help you manage your chart of accounts and reports:

• Understand the chart of accounts in QuickBooks
• Customise reports in QuickBooks Online

Reach out to me if there's anything else that you need. You take care and have a good one!