You can change the settings for job uploaders that are enabled by navigating to Admin->Job Boards and pressing the "Advanced" button at the top of the page.*
Click the warning popup that appears notify you that entering incorrect information may cause the job board to stop functioning. Select the Job Board you require from the dropdown list and alter the details as required. Don't forget to press "Save"!
The job uploader should now be enabled with the new details.
*Please note that the above operation should only be performed if you or the job board have changed the login details needed to post jobs.