Changes to the parameter defaultValue in Jenkinsfile are not reflected in existing Jenkins job after executing the job.

• use following parameter definition:

properties([
    parameters([
        string(name: 'EXCLUDE', defaultValue: 'pattern', description: 'description'),
    ]),
]) 

• add new job and run it for the first time, go to job configuration - the job should now have this parameter with "pattern' default value
• change in the Jenkinsfile pattern to "pattern2"
• run the job again and go to job configuration - the job will still have the old value "pattern"