Launchscreen imageview is not in center position on IOS

Hi,

I tried to make the launchscreen, following the microsoft link, but it's a total nightmare. When I change simulator device then the full image change it's position from central to the side.
In the Viewing of the designer I use IPhone 8 Plus, set the image etc. Then I change to IPhone SE and then the whole image move to the left. What do i'm doing wrongly?
Many thanks in advance!