Navigate to the Settings tab, then click on the Journals link. Alternatively, activate the Journals tab for permanent display.
You can opt to clone (copy) or reverse a journal directly from the Actions column in the journal list or you can first view an existing journal and click on the Clone or Reverse button in the overview screen.
Please note that cloning and reversing both create a new journal transaction with a unique Transaction Id. The reverse option copies the original but switches the debit and credits around.