"now all my banners are visible at the same time...."
Not sure what you mean, sorry...
Slick takes each slide and wraps it in what you see in the screenshot.
You have just an image field, so that gets wrapped by div.slick-item
Next you see the modal links applied by seblod's image settings. I turn this off. If I want modals I turn on the modal option in template setting and set it to Bootstrap 3. Provide a class name ('my-slick-modal'), then add as an attribute to any appropriate fields in 'element' position: data-toggle="modal" data-target="my-slick-modal')
In the you will see the outputted js. Can you post that, see what settings you have.