Please make sure the images are of following sizes(px)

Custom Logo: 270 X 60

Slider Image: 1920 X 967

Community Section ( HomePage ): 960 X 450

Post Featured Image( With Sidebar): 780 X 437

Post Featured Image( Without Sidebar): 1200 X 437

Featured Post Image ( Widget): 275 X 275

Recent Post Image ( Widget): 75 X 75

Donation single page: 780 X 520

Homepage donation section: 380 X 270