need help - handout image size

i applied to become a marketplace creator, and i got a reply i need an almost finished product to be considered.  i'm testing and uploading things for the campaign i DM and i noticed when i upload images as a handout, the images are small.  when i purchase things from the marketplace, sometimes there are big image handouts.  how can i make my handout image bigger for people who have larger than like 400x400 screens so it takes up more of the screen when you click on the handout and the image shows?  i tried increasing the resolution but it still shows a small size.  

1000x1000 jpg minimum

ok this didn't exactly solve my problem, because i uploaded a pic in a handout and it shows at a huge resolution, but even uploading another pic the exact same way with identical resolution, bit depth, etc didn't do it.  both were way above 1k by 1k.  i tried 1x1 resolutions, resolutions under and over 1k on each side.  i found in the handout the players can click on the image and it opens bigger.  that's good enough.  it's a shame i can't figure out why some images in handouts open at a huge size and some at a size like 400x400 in the handout.  again at least players can click on the image in the handout to open it bigger, basically a type of zoom in.