Unable to set expiration of cache images greater than 24 hours

Macular-Degeneration-Vitamins.com is installed on WPEngine, and the site uses WPEngine’s CDN.

All load speed testing services (Google PageSpeed, YSlow, WebPageTest.Org) state that images cache are set to expire in 24 hours.

But my browser cache settings are:

Set Expires Header: Selected
Set Cache Control Header: Selected
Set Entity Tag: Not Selected
Set W3 Total Cache Header: Selected
Set Expires Header: Selected

Media and Other Files Settings:
Expires Header Lifetime: 31536000 Seconds
Set Cache Control Header: Selected
Cache Control Policy: Cache with Validation
Set Entity Tag: Not Selected
Set W3 Total Cache Header: Selected