Job to change the same database user password across multiple databases fails

OEM 13.5

I have a need to automate password rotation for several of our "service" userids across multiple databases. The password for each userid needs to be the same in each database. I have been testing this out on 2 databases with 1 userid in both databases before scaling up. The job works if I create two named credentials with scope of Target (one named credential for each target database).

However this is not practical to do this with 5 userids across more than 1 hundred databases - I would have to create hundreds of named credentials with a scope of target. I instead created for my test, 1 named credential of scope Global for the userid I am testing in the 2 databases. However, when I run the job, it fails stating that it can't find any named credentials for the two databases I am running the job against.