Configure expires headers on S3 bucket or turn off to expire the headers on my web server?

I have set up EasySocial to use an Amazon S3 bucket for the images. Right now when I run tests at places like GTmetrix I am being told to fix the lack expired headers on those images. Do you know how to set a header expiration?

Otherwise, might I be better off turning off the S3 bucket and storing them on my server there there are header expirations set. Here you can see how most of the items without the expiring header are those images:

Leverage browser caching
F (38)
SERVER HIGH
What's this mean?
Leverage browser caching for the following cacheable resources:

https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2782/e97443984f38929b5fb8ccae78a18950_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2788/03411e2fe52994fa2e6daf0662ddee30_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2802/98c1684691a8b7b0de29368b62df79da_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2804/c896969bbc54ac522efe8c9a2a7963e7_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2806/e9a454ae5c3fe263c4fa2958cdeefd39_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2807/8de5ca62d836916b45693f41af0e57c0_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2811/1765103450dd9f788a4abcaf6bdd22eb_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2813/f4206049fc9d028b83937d08122d5c18_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2815/6d1f6f362eff4ac86d1f152ab0375f60_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/2825/ce27a58e9fef958a71c62e7a6a4b8b15_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/813/dcf11f423dc45818de20d152f6564219_medium.jpg (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/816/f67eefed1822be9c44b9d174a4913279_medium.png (expiration not specified)
https://s3.amazonaws.com/drcarney-com/media/com_easysocial/avatars/users/828/2418f860b97c69991e345bb8b6437470_medium.jpg (expiration not specified)
https://connect.facebook.net/en_US/sdk.js (20 minutes)