Hello Almanzor,
It seems as though, for some reason, the .uproject files for 4.11 aren’t being associated with the engine itself. To fix this, you should be able to right-click the .uproject file in question, select “Open With” and then if Unreal Engine isn’t listed in the next window, press Browse and navigate to your installation for 4.11. My path is as follows, for reference:
C:\Program Files\Epic Games\4.11\Engine\Binaries\Win64
Once at that location, select UE4Editor.exe and it should associate those .uproject files with that version of the engine. If it doesn’t work correctly, please let me know what the results were.