Thank you so much to both of you.
Finally, looking carefully it seemed to have badly the size of the screen. At the time when I started I chose the size of an Iphone 6+ but apparently it was not the right one and when I put the size right it already occupies the full screen when I publish it.
But when I see it on the mobile, you can move the screen, do you know how I can block it so that it does not move up and down?
On the other hand, in order to appear well published, do the screens have to be right in the corner of axure? Can not I put them in the center of the axure screen and then be published as well?