Problem with featured image

I’ve a problem with the setup of my WPTouch because my featured image or slider image I don’t really know how it’s called but the image on the top of my website. It isn’t working on mobile version trough WPTouch because on 2 of the 4 pages you can only see one bit of the image and not the whole image and on the other 2 pages there is just no image.
And I even deleted the image that is shown but it just won’t update.
I’ve tried deleting files trough a FTP client and re-installing the plugin twice but it doesn’t work.

I hope anyone can help me