Action box collider limit

I try to make a game, and I cannot save on a diferent level the the 1 i spawn the player on, so I try to use an Action bp with a box collider. But the colider need to be 3200 cm on the x axis, 3200 cm on the y-axis and 5000cm on the z-axis.
but unreal engine 4 won’t load the stream level.
is this a bug or is it a setting I need to edit or what???
If only someone in this world can make a tutorial on youtube about a save betwin difernt levelds.