The feature that allows you to show account number might have been turned off, ngrantwci.
Let's go to your company settings and make sure it's turned on back again. Here's how:
- Go to the Gear icon and select Account and Settings.
- Proceed to the Advanced tab.
- Look for Chart of Accounts and click on it.
- Make sure the Enable account numbers feature is turned on and the Show account numbers box is checked.
- Click Save, then Done.
Once done, let's go back to the Chart of Accounts and check if you can already see the account numbers. You'll also need to manually enter the numbers again in case the numbers were deleted. Here's how:
- Click the drop-down list beside View register, then select Edit.
- Enter the account number in the Number field.
- Click Save and close.
More details about managing your Chart of Accounts are also discussed here:
I'd be glad to help you again if you need more help when working in QuickBooks Online.