Use the cautil command. If it is global change to all jobsets/jobs just use an * and then type in the new user id and password. You can also use the * as just a wildcard like tes*
cautil SELect JOBPARM ID=(jobset-name,job-name,jno)
SUBFILE=executable-filename
SUBUSER=submit-user-id
[PARMn=(parm-value)]
[SUBDOMAIN=domain_controller_name]
[SUBPASS=password]