I have been trying to open and run my couple-months old project in Unity3D, and I'm getting about 500 errors. So idecided to reinstall Unity. On the tutorial for the project, it tells us to make sure the "Scripting Runtime Version" is set to 4.x equivalent. Only problem for me is I cannot see such an option in Unity5.5.4p4. How can I set .NET 4.x in Unity for good?