Futrli's 'Override Journal Defaults' option allow you to override the Forecast Item's default behaviours. You can use the advanced options to change an entry from a debit to a credit, or from a credit to a debit, to change the Bank Account, Accounts Receivable or Accounts Payable line the item will impact, or to set the Forecast Item to a 'No Cash' entry.
Advanced options can be selected in the bottom right of the Forecast Item by clicking 'Override Journal Defaults':
To set a Forecast Item to 'No Cash', please see the following Help Guide.
To override the debit or credit settings, please see this Help Guide.