White screen before Splash screen change to black

Hello everybody, When I launch my game on android white screen shows for second what is annoying. How can I change this white screen to black? I was searching and I found that I can probably change it when i create AndroidManifest.xml and add there
"item name="android:windowBackground">@null/item" but when I tried it I got errors that unity can't merge AndroidManifest so I renamed my AndroidManifest and I didn't have no errors but nothing changed. Am i on right way or what should I do? I have these xml files in Assets>Plugins>Android link text link text