@deanishe
Thank you very much for your reply, but it seems not.
My System is
OS: Mojave 10.14.6
Alfred: Alfred 4.0.9 PowerPack
If it's not controllable in my version, I will change my system then (coz I love Alfred and like to use).
I just wonder why and how....
As I stated in first comment, I already looked for all Library/Preferences/*.plist.