Application contains so called left layer panel that's used mainly for mapping, change the visibility or the order of layers in the  project.  To open left panel tap on button (1) in the map screen. 

Change layer visibility

To display or hide layer open left layer panel and tap on the layer in the list. The highlighted layer (2) is shown in the map view.

Change layer order

The order in the layer panel defines the order of layers in the map view. To change the order simply drag & drop layer on the left age of panel (4).