Can't change none-layer, no-effect background

[joseph martin5E36]

Hi good day 😄

Can't seem to change the color of a background since it doesn't have any layer or effect on it.
I already check the compostion setting and it show black BG but this file has a blue BG that i cant seem to

find the cause.
Please help me from this despair. Thank you 

[joseph martin5E36]

I got it now there were layers that are hidden, unhide it by clicking the icon (looks like T Alien) between Draft 3D and Enable frame blending. lol

[Rick Gerard]

For most formats, the composition background color will render as black. If you want a colored background, put a comp-sized layer on the bottom. Check the Transparency Grid. If you see the checkerboard anywhere and you want any color in the background, add a solid so there are no transparent pixels.