[otrs] Can't change the system ID

Hello, I am testing OTRS for windows V2.4.7. I have installed it and it works well. Now I want to change the System ID. I do this as administrator in Sysconfig --> Framework::Core::SystemID. There I change it from 10 to 9 and then Update. After the update is "jumps" back to 10. I try a restart of the services but this has no effect. How can I change the System ID? Best Regards, Jurjen Verhoeff