HTTPs Headers too long/too many requests

I have a website powered by Prestashop. Through testing and optimization we have come across a common issue across other Prestashop websites as well; Header requests being either useless and the set-cookie being too long.

There are 53 response(s) that sets both a max-age and expires header. There are 3 response(s) that sets a pragma no-cache header (that is a request header). There are 55 response(s) that sets a server header.

ADVICES

Avoid Unnecessary Headers
Do not send headers that you don't need. We look for p3p, cache-control and max-age, pragma, server and x-frame-options headers. Have a look at Andrew Betts - Headers for Hackers talk as a guide https://www.youtube.com/watch?v=k92ZbrY815c or read https://www.fastly.com/blog/headers-we-dont-want.

ERRORS

https://WEBSITE.com/
https://WEBSITE.com/
https://WEBSITE.com/
https://WEBSITE.com/themes/THEMENAME/assets/css/theme.css
https://WEBSITE.com/themes/THEMENAME/assets/css/theme.css
https://WEBSITE.com/modules/paypal/views/css/paypal_fo.css
https://WEBSITE.com/modules/paypal/views/css/paypal_fo.css

So I have been trying to edit several index.php files trying to follow the links given to me but I am finding little to no result whenever I attempt this test again (through speed.host). Is there a way I can massively change the way my directories are indexed to be optimized? This is how the regular index.php is, by default, from Prestashop:

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");

header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

header("Location: ../");
exit;