If your test is in a package, which it should be, then you can’t set it from the test. Packages cannot have hierarchical references to any instances of modules or interfaces. So you have to set it from TB_top or some other module instance.
If your test is in a package, which it should be, then you can’t set it from the test. Packages cannot have hierarchical references to any instances of modules or interfaces. So you have to set it from TB_top or some other module instance.