My apologies if this has been covered elsewhere - I tried to do a search in the forums and it returned no results, regardless of the word or phrase I searched for.
In the Storyline online tutorial on Layers (Adding and Editing Layers), in the section called Rearranging Your Layers, the documentatoin says that layers appear in the (Z) order as they appear in your Layers panel. So if I have layers 1, 2, and 3, with layer 1 at the bottom of my layers panel and 3 at the top, and I then display those three layers in my lesson, the three layers should appear stacked in that order when viewing my project. Layer 1 should be on the bottom, then 2, then 3 on top.
However, it actually depends on the sequence in which you display them. If I use a trigger to display layer 3 first (which should be on top) and then another trigger displays layer 1, layer 1 will appear on top of layer 3. In certain situations that would be useful, but for others (including what I am currently trying to accomplish in a Storyline file) that is not so helpful. I need to be able to completely control the Z order of the layers by setting their order in the Layer panel as described in the documentation, but unfortunately that isn't the case.
Just wanted to pass this along in case someone else is having issues with layer order.