All of the social media platforms such a Facebook, Twitter and LinkedIn "cache" the initial images or text associated with a website. Cache is a technical term that basically means a temporary save. Caching speeds up load times and has many benefits for web users but in can mean that a social media platform is 'remembering' old information that it stored from a previous share.
Fortunately, clearing the cache is easy and each of the platforms provides a method for you (or us) to update the image and text pulled.
Here is a helpful article summarizing the best way to accomplish this on all of the platforms.
To update the 'website card' on Twitter, simply go to Twitter's Card Validator Tool
Enter the web address for your Swell Site
Click Preview Card
Here is an example: