The choice of bookcover is usually done by the publishers, some of whom have their own graphical design unit. Naturally they come up with covers which are intended to make people want to read the book.
Sometimes an author can refuse a bookcover if they really dislike it for some reason, and the publishers then offer another cover, but I haven't heard of an author having control of covers.
You can certainly suggest your own cover, but if it is seen as too weird/boring/unappealing etc. then it probably won't get chosen.