If you want to take control of what Facebook crawler picks up from your page you can use our Search & Social settings and you will share only the information you like with your followers.
1. Go to the Search & Social section of your page;
2. Choose Image and upload the picture you want to show in your Facebook post. In order to take up the full width of the post, you will have to use a picture size of 1200 x 627.
3. Add your own message and description and save your page;
If your information is cached, go to Facebook's Debug Tool; First click on 'show existing scrape information';
Then click on 'fetch new scrape information';
Congratulations, your new information will appear when you share your page on Facebook.
To achieve the same thing with LinkedIn, you can use their Post Inspector tool to fetch new information for the page instead of showing the old cached one. You can find it here: https://www.linkedin.com/post-inspector/
Add the URL of your page in the dedicated text box and then click Inspect.