Board Thread:Ask the Staff/@comment-26693477-20200104130931/@comment-5956954-20200113042747

It appears you found out to do so, since the image is now replaced. For those who don't know:
 * Click on the image in question.
 * If it takes you to a different page, look for the (!) mark on the image.
 * If unclickable, right-click to new tab and edit the URL to include only steven-universe.fandom.com/wiki/File:whatevername.extensionname
 * Click the file name of the image on the top left.
 * Hover over "edit" and click "replace"
 * Replace the image with your version.

See Help:Contents in the future to answer such frequently asked questions, or like me when I was new, go around and experiment by clicking on things.