How can i get a black night sky?

My English is not as good as I expect,also I am a Freshman in UE4,hope I can express myself well.
I know this question has been asked before,but it was solved with C++ program.I‘m wondering if there is some solutions that I can use with Blueprint.

P.S.I have already changed the direction light angel,but still the sky looks very bright

Thank you!

Rotate the directional light until it’s arrow is pointing up, then select the skysphereBP and in the Default section for the variables you’ll see “Refresh Material” check that box and you should see this:

thank you for the help,I’ve checked the "Refresh Material"box, but it just like the picture shown upon =.,= I have no idea about it

Ok set your source light to this rotation X -180 Y 90 Z -180 and then click on the Refresh Material again it should now go to a night sky like my screenshot

Another option is to remove the Directional Light Actor from the Sky Sphere BP and the adjust the Sun Height variable:

This time it fially turn dark~~I should learn more about the directional light.

Thank you so much!!!