To add a meta keyword, click the sector and validate by pressing "Return". It is possible to take out tags by clicking the cross. Canonical URLs are applied to stay away from duplicate written content and to point to engines like google that is the “original” site. It is actually https://addons.prestashop.com/de/seo-suchmaschinenranking-optimization/31857-automatische-google-rich-snippets-json-ld-opengraph-seo.html