How to adjust the crop of the YouTube banner: By default, the viewport is centred on the screen, meaning the panoramic crops will show the full-width of the image through a narrow part of the middle.

YouTube banner size. Your banner needs to be specific pixel dimensions to format correctly on YouTube: Recommended banner size: 2,560 x 1,440 pixels; Minimum banner size: 2,048 x 1,152 pixels; ...