Overview of where a course cover image appears
A course cover image shows within the circle on a course card (for learners).
And when a learner goes into the course, it's shown as the banner.
How to upload/replace your cover image
When you are in the main course editing view, head to Cover photo. Then choose to add or Replace file.
Then drag and drop or choose your file.
The uploader shows a preview of your image. You can then drag and position the points on the rectangle to choose exactly how you want your image cropped (to a constrained ratio that works for the banner).
Then Save and you're all done.
How to choose a suitable image
For cover images you want something that:
doesn't have words or details that need to be read,
has a suitable wide (but short) section of the image, because banners are wide and short.
Note: iQualify is responsive and can be used on all kinds of devices, so the banner does resize based on the device someone is using.
For instance, the image of the earth would not be suitable as you would only see a section of the image.
Preferable would be an image like the one below which is more like a banner.