Changing starting slide when it is pointed to from the other slide

Hi there,

I am trying to create a custom slide instead of the lightbox slide, as it is apparently not possible to edit the graphic look and feel of the lightbox slide.

So I created a custom slide, which is pointed to from the player topbar left.
The custom slide has a button to close it and it points to the slide which I want to be seen first when the project starts.
However, the project is rendered from the start with the custom "lightbox" slide, which I have to close first in order to be able to see the desired starting slide. I also cannot change their order by dragging them around.
Is there a way to show custom slide only when clicking the link on the topbar of the player? Or, is there a way to change the look and feel of the lightbox slide as an alternative?

Thank you very much.