Hi. You should clean the cache of your site on Facebook side.
https://developers.facebook.com/tools/debug/
And the same thing must be done with any other social networks. This must be done every time after making changes on the site.
If you at least once share a link to your site in a social network, it immediately places in the social network cache. Otherwise, social networks simply could not work because of excessive load. Since millions of users, every day publish links to sites.
To change the display of your site, it is necessary to clean this cache. Each network has the appropriate tools for this.
If there are no such tools in some social network, then you just need to wait until the social network cache is updated. It can take from several days to several weeks, depending on caching settings on the social network side.