Setting up account codes

I am trying to set up account codes in my chart of accounts. I have selected 'Set Period ’ on the summary page, but it does not give me the availability to check mark Account Codes. Nor does it give me options to select Cash or Accrual.
Do I need to select something else?

To set up Account Codes go to Settings > Chart of Accounts and edit the individual account.

You will only see this check mark if Account Codes have been setup under Settings > Chart of Accounts.

Read this topic where this is under discussion Cash Basis Accounting - #2 by Tut

I have been to Settings > Chart of Accounts, I have edited each account and allocated a number, but when I go to edit it again, the code number has disappeared.

Did you click “Update” after editing ?

Yes, but when I go back in, the number is gone.

So you have an Account without a code

You enter an Account Code

After clicking “Update” you should see the code next to the Account name

Then clicking on Set Period you should see

If not, what Edition / version are you on