Facebook uses its own criteria to decide which images and texts to display in the preview of a shared link.
Help Facebook decide
Make sure that the image that you want to appear in your Facebook Preview is not too small. Plus it has to be at the very top of your Dolphin website.
Even if you decide to replace the picture that’s currently being previewed, Facebook may still continue to use it. To update Facebook Preview, you'll have to use the Facebook Debugger.
Use Facebook Debugger
- Go to: https://developers.facebook.com/tools/debug/
- Enter the URL for the website for which you’d like to update the Preview and click on Debug
- In the following window you can click Scrape Again
- Your content will be updated