Why page speed score are not increasing in WordPress?

Question

GTMetrix Speed Score is not increasing This Website Shows 4 types of problems for speed issues. Problems are:

1. Defer parsing of JavaScript
2. Leverage browser caching
3. Minimize redirects
4. Serve scaled images

For Defer parsing of JavaScript, I used the following code in function.php in theme editor

 function defer_parsing_of_js( $url ) {
     if ( is_user_logged_in() ) return $url; //don't break WP Admin
     if ( FALSE === strpos( $url, '.js' ) ) return $url;
     if ( strpos( $url, 'jquery.js' ) ) return $url;
     return str_replace( ' src', ' defer src', $url ); } add_filter( 'script_loader_tag', 'defer_parsing_of_js', 10 );

Leverage Browser Caching

For Leverage browser caching, I used the following code in .htaccess

<IfModule mod_expires.c>   ExpiresActive On   ExpiresByType image/jpg "access 1 year"   ExpiresByType image/jpeg
 "access 1 year"   ExpiresByType image/gif "access 1 year"  
 ExpiresByType image/png "access 1 year"   ExpiresByType text/css
 "access 1 month"   ExpiresByType text/html "access 1 month"  
 ExpiresByType application/pdf "access 1 month"   ExpiresByType
 text/x-javascript "access 1 month"   ExpiresByType
 application/x-shockwave-flash "access 1 month"   ExpiresByType
 image/x-icon "access 1 year"   ExpiresDefault "access 1 month"
 </IfModule> <IfModule mod_headers.c>   <filesmatch
 "\.(ico|flv|jpg|jpeg|png|gif|css|swf)$">   Header set Cache-Control
 "max-age=2678400, public"   </filesmatch>   <filesmatch
 "\.(html|htm)$">   Header set Cache-Control "max-age=7200, private,
 must-revalidate"   </filesmatch>   <filesmatch "\.(pdf)$">   Header
 set Cache-Control "max-age=86400, public"   </filesmatch>  
 <filesmatch "\.(js)$">   Header set Cache-Control "max-age=2678400,
 private"   </filesmatch> </IfModule>

For Serve scaled images

I did it manually from the file manager.

But the speed score is not increasing in any way. it remains the same.

What could be the solution?