not all images optimized especially png files

hi, i smuch all images, but still google speed test shows below :
Compressing and resizing https://www.talentsroot.com/wp-content/uploads/2018/07/waqas2.png could save 1.9MiB (99% reduction).
Compressing https://www.talentsroot.com/…wp-content/uploads/2018/07/english-1.jpg could save 381.4KiB (75% reduction).
Compressing and resizing https://www.talentsroot.com/…/unique-animation-custom-intro-video.png could save 239.2KiB (90% reduction).
Compressing and resizing https://www.talentsroot.com/…-content/uploads/2018/07/photo.jpg-1.png could save 89.5KiB (98% reduction).
Compressing and resizing https://www.talentsroot.com/…tent/uploads/2018/07/hotel-ewerest_2.png could save 27KiB (58% reduction).
Compressing and resizing https://www.talentsroot.com/…/uploads/2018/07/talentsroot-whitall.png could save 1.4KiB (25% reduction).

please advise