Hi,
Atopia, maybe late for you, but I hope it helps other users. I found the “sticky” option. You can select it on the Publish section -right side bar- when you are editing a post, under visibility menu.
As far as I understand, if you do not set up any post as sticky, by default magazino displays about 10 posts. Once you set up a post as sticky, the ones not marked as sticky do not appear anymore. So, if you want only 1 post in the slider, mark as sticky only this post, if you want 2 posts, mark both, and so on.
Cheers,
