Please note, if you have already chosen to Reconcile to online balance, you will not see the Auto Reconcile option as being available to select. You will need to go to Tools > Account List and click Edit next to the account you want to Auto Reconcile.
In the Account Details windows, go to the Online Services tab and uncheck Reconcile using online balance in the bottom right corner. You will now be able to follow the steps outlined above to enable Auto Reconcile and also have the option to Reconcile to online balance again.
It looks like you're new here. If you want to get involved, click one of these buttons!