You are not authorized to change message severity for enabled usages.

What causes this issue?

You tried to change the message severity for a rule which is enabled for
at least one usage in a check scenario. As this has an impact on the
according process flow you need a special authorization.

System Response

You are not authorized to do the change.

How to fix this error?

Request the authorization for enabling the corresponding usages.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.