Before you start:
The following steps show you how to modify a Configuration Manager's database password, User Name Server queue manager, and the maximum JVM heap size:
You cannot change all the parameters with which you created a Configuration Manager. If you cannot modify a parameter that you need to change using the changeconfigmger command, delete the Configuration Manager and then create a new one. This will allow you to redefine all the parameters.
See mqsichangeconfigmgr command for further information on these parameters.