Leverage browser caching

I made a test on Google pagespeed insights to see how my page fast. I got one error which say "he following cacheable resources have a short freshness lifetime. Specify an expiry of at least one week in the future for the following resources"
http://www.mysite.com/templates/gk_leag ... attern.jpg (9.6 minutes)
http://www.mysite.com/templates/gk_leag ... /blank.gif (30 minutes)
http://www.mysite.com/templates/gk_leag ... g_main.jpg (30 minutes)

there isn't any other error. How can I specify an expiry time for these image. I'm using below codes in my .htaccess
<IfModule mod_expires.c>
ExpiresActive On
ExpiresByType image/png A1555200
ExpiresByType text/javascript A1555200
ExpiresByType image/jpeg A1555200
ExpiresByType image/gif A1555200
ExpiresByType text/css A1555200
ExpiresByType image/x-png A1555200
ExpiresByType application/x-javascript A1555200
</IfModule>

Hi

Can You please send ma an access to Your joomla panel ?