Thanks for your message, I would be happy to help you out with this. It all depends on what image you are trying to change, can you share your store URL and send a link to the specific page? One thing to note, is most of your images would be uploaded by heading to Online Store>Themes>Customize in your Shopify admin.
Feel free to reach back out here with that further context and I would be happy to take a closer look with you!
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