Changing CSS FilePath for All Pages

You can override your Header <head> ... </head> in the header.php of your Theme.

I prefere you create a Childtheme, if you don’t know how, let me google that for you 😉.

And than simply copy your header.php from your Parent Theme in /wp-content/themes/your-theme to /wp-content/themes/your-child-theme (replace the theme dir with yours).

And add your styles after <?php wp_head(); ?> and before </head> like normally css-styles will add:

<link rel="stylesheet" href="https://wordpress.stackexchange.com/wp-content/themes/your-child-theme/css/yourStylesheet.css" type="text/css" media="all" />

The Styles will add to each page.

Hope it helps.