You can create and manage existing sign off steps if you are logged in as a Jira administrator.
Under Jira administration click Issues and then click Sign Off Steps. You will see a page which lists any steps that have been added already.
Create a new Step
At the bottom of the table which shows existing steps, you may enter the name for a new step. You may also select projects or issue types under which the step will be visible. The default is all projects and all issue types. When you have entered the name for the new sign off step, and selected projects and issue types as required, click the Add button. Your new step will be created. Once you have added a new step, it is highly recommended that you complete re-index of Jira.
Modify a Step
You can alter a sign off step after it has been created. To modify an existing step, click on one of the row for the step that you would like to change. The name, projects and issue types will become editable and you can alter as needed. To save your changes click the Update button at the end of the row. You may discard any changes by clicking the Cancel link at the far end of the row.
Deleting a Step
If you would like to delete a step, click the Delete button in the row for the step that you wish to delete. You will be presented with confirmation message, click Confirm to confirm deletion. Once a step has been deleted it cannot be undone.