When you change the preference variables at runtime, sometimes you will these values were rolled back to your composite value.
This will happen because of server restarts. Whenever your SOA servers get restarted , these values will be reverted to the original value.
To resolve this issue, you have follow below steps.
Right click on your SOA-INFRA and navigate to Administration –> System MBean Browser.
Now go to Application Defined MBeans –> oracle.soa.config –> Server: soa_server1 –> SCAComposite –> Project1–> SCAComposite.SCAComponent–>BpelProcess1
In the BPEL just change the value of your preference variable and click Apply.
Now in the MBean configuration,go to Operations tab and then click on save.
It will open a new window,click on Invoke to SAVE the changes permanently.