I've changed meta image and description, but when I click "Share" button, all data stay the same (unchanged). What should I do?

The case is, after the first circulation to the page, Facebook caches an information about it. These data from the cache are used during the next 24 hours.
That is why the changes are not displayed. You can wait for 24 hours and check changes, or you can forcibly update the information about your page on Facebook:
1) Go to https://developers.facebook.com/tools/debug/og/object/;
2) Enter URL of your page in "Input URL" field and click "Fetch new scrape information" button.
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