You can replace an image either on the 'Edit Scene' modal or the 'Advanced Editing' screen using the same process. Here are the steps:
Step 1: Select the image that you want to change.
Step 2: Go to the 'Media' tab and find an image that you like.
Step 3: Drag and drop the image into the scene.
Step 4: Click 'Replace.'
Here is a look at how to change an existing image in a scene.