You can quickly change out images in a post or a page. If you want to replace an image that is in one of your posts or pages, click on the image and select the Edit icon. A Window will open showing the Image Details. Under the image there will be a Edit Original button and a Replace button.
Click the Replace button and you’ll be shown your Media Library where you can select a new image. Then click the Replace button to replace the image or the Back button or top right “X” to cancel the command.