What was done on your board was combining all the individual CSS files into one file. It had nothing to do with changing the amount of time a file remains in a browser's cache.
On this board, I control the cache time using the
function in the
files. Since you serve a
file, you can control the cache time by adding the following block of code to the
file in your root (public_html) directory:
Header unset ETag
Header set Cache-Control "max-age=605000, public, must-revalidate"
The above code will set the cache time to 605000 seconds, or approximately one week, for resource files served from your site.
Please be careful when editing
files...a mistake can cause everyone to lose access to your site!