Extremely Long Load Time on Website

Thanks very much!

The GTMetrix says to combine multiple js and css files into one file for each. Since some of these styles and scripts are linked to their respective plugins, how do I redirect the paths to link to the new all-in-one css or js file?

Also, how do I lengthen the browser cache expiration for many of these files? I’d estimate 97% of these files are core design elements which don’t need to be updated.

Again, many thanks in advance for pointing me in the right direction!

Sincerely,
Jane