In X-Plane, the load order of sceneries is absolutely crucial! The load order of sceneries is defined by the scenery_packs.ini located in the Custom Scenery folder. It is a plain text file, you can open it in any text editor you like (I recommend Notepad++). The system is very intuitive, packages higher in the ini have a higher priority. That is, a package at the top takes precedence over a package at the bottom.
How to order packages
In general, packages should be ordered in the order of Custom Airports/Sceneries > Generic Airports > Overlays > Meshes > Libraries. (Libraries can go anyway actually, doesn't matter unless they conflict, then the one higher takes precedence). So your order should be something like this