Use the character-based interface and the Work With Job Description
(WRKJOBD) command or the Change Job Description (CHGJOBD)
command to change job descriptions.
Command: Change Job Description (CHGJOBD)
All jobs that are started after the job description is
changed that use that job description are affected. If you have changed a
job parameter to something different than the what is specified in the job
description, that parameter will not be affected.