when you import image for background ! important you have retina x1 x2 x1.5 x4 if you use 1x the file picture will be the same size as the file you have in your computer ex : 640x480 picture imported at 1x its same size ! but imported at x2 it will be 320x240 half its size! reimport the backgrounds image by deleting the frame or animation of actor if its an actor! if its a simple background just simply delete old frame add new frame! dont use import over old frame cause then you will use same retina you used before to make image smaller! in you case i think is x4 but try setting it at x1 if its a 640x480 game or other custom file !