Changing the preview on YouTube can be accomplished by following a few basic steps. First, navigate to your YouTube video manager and select the video you wish to edit. Next, click on the “Details” tab and scroll down to the “Thumbnail” section. Here, you can select from a list of pre-made thumbnails or upload your own custom image. Once you have selected the thumbnail you want to use, click “Save” to make the change. It’s important to note that it may take a few moments for the new thumbnail to appear on your video. Changing the preview image can help attract more viewers to your video and make it stand out on YouTube.