What I am trying to say is:
- You import a shapefile into an empty QGIS and the QGIS environment gets the projection system of the imported shapefile.
- You import another shapefile into QGIS. The projection system assigned earlier by the previous shapefile remains in place for the QGIS environment.
- But, when you import a basemap using the OpenLayers plugin, the environment gets the projection system of the imported basemap.
Why doesn't QGIS just follow one standard by keeping the projection system that was assigned by the first layer imported into its environment?
Note: I have tried this with QGIS 2.10.1 only.