using System;

using System.Collections.Generic;

using System.Linq;

​

public class Test

{

    public string A { get; set; }

}

public class Program

{

    public static void Main()

    {

        var tests = new List<Test>()

        {

            new Test()

            {

                A = "Initial String",

            }

        };

        var test1 = tests.First();

        test1.A = "Updated String";

        foreach (var test in tests)

        {

            Console.WriteLine(test.A);

        }

    }

}