It's possible that you've turned off the Use account numbers option, swcs61.
Just a heads up, before changing your account number you'll have to deactivate the account first.
Then, here's how to enable the Use account number feature.
- From the Edit menu, select Preferences.
- Select Accounting .
- Go to the Company Preferences tab.
- Tick (✓) the Use account numbers field.
- Click OK.

Afterward, go back to your chart of accounts, and then you'll have now the option to edit the numbers.

I'll be right here to help you anytime.