An image looking right on your computer doesn't confirm that the right file landed in the right slot.
After uploading, look at the store preview:
- Can you read the headline at that size?
- Does the image show the feature it promises?
- Is the layout correct for the device?
- Are the screenshots in the order you intended?
Show people what they'll actually do in your app. Then check what the store will actually show them.
Check the saved result, not just the file you started with.