Help making external links (post titles and featured images) open in new tab

I’ve tried jquery, but it’s not working.

The script I tried is:
jQuery("a[href^='http']").not("[href*='keto.hu']").attr('target','_blank');
It’s somewhere in the head section, you can find it.

This is the tag archive, where my external link-posts are: keto.hu/cimke/fb-recept

I’ve also tried 3 plugins for external links: “Open external links in a new window”, “WP External Links (nofollow new window seo)”, “WP Links”
and none of them is working for my external posts so i tried to add jquery with “Insert Headers and Footers” script but it’s not working (i made other jquery scripts with this plugin that work).

Please help me! ??