The thumbnails for your Galleries can be managed from the Galleries area of Crevado admin:
How do I change the order of the thumbnails?
You can reorder your Gallery thumbnails simply by dragging and dropping the thumbnail into the desired position.
Changing the Thumbnail Image
Changing the thumbnail image is easy. Hover your mouse over the Gallery thumbnail you want to change and click the cog icon which appears on the top right of the thumbnail. To change a thumbnail to an alternative image, click Change Thumbnail:
You can then choose to either upload a new image or select an existing image from the Gallery which can be used to represent it. It’s wise to customize the layout of your galleries first and then crop accordingly once you’ve settled on the desired layout.
Cropping an Existing Thumbnail
The default cropping applied to your Gallery thumbnail may not suit every type of image, in these cases you may wish to manually adjust the cropping for maximum impact.
Hover your mouse over the Gallery thumbnail you want to change and click the cog icon which appears on the top right of the thumbnail. From the dropdown menu click Adjust Cropping :
From the cropping page, you’ll see a yellow box which represents the target cropping area
You can resize the crop area by dragging and dropping the resize squares located at the edges of the yellow crop area. To move the crop area itself simply drag and drop it.
Note: Underneath the cropping area you’ll see a preview image which shows you how the cropped image will look should you save the changes.
To save your changes click Crop It!
Your Gallery thumbnail has now been updated to use the cropped version of the image.