If you are referring to a change when you resize your LO, try this.
- First, merge all the visible layers. I always work on a duplicate image so I don't accidentally lose my pspimage with the layers. Use Window, Duplicate to get another copy.
- Then resize the LO.
- Use the unsharp mask on the LO. It's under Adjust, Sharpness. This will make both your photos and anything else on the layout clearer. You always lose sharpness when you resize an image.
- Finally, save as a jpg using the optimizer to make the needed file size. Set the compression value as low as possible and still meet the file size you need.