Just remove pixelation W/H to keep the same size.
If the image is 512x and you set pixelation 4, then will be exported at 128x, because 512/4=128 to give you the real 1:1 aspect ratio.
If you want the pixelated version, after export, in PSP ot other software just resize the image X times you want to get 4x,8x,6x or what you want.