For impersonation to work, some valid Test Settings should be created and saved. It's important that the main ROR setting will be unaffected, so you, as an admin/user don't need to worry that you will break something. Here is how to write test settings:
Open the ROR menu
Click the Edit security settings button
Test settings ror menu
Go into the Test settings tab
You can set the "time to live" (TTL), which is a time interval after which the test settings will be automatically deactivated and impersonation session will also abruptly exit