Changing object in a Form through a Class

Hello, I want to state a problem for which wherever I have searched for help, I cannot get an answer.

In C# 2008, I have the main form called Form1 and a class called Class1 containing a function which is summoned from the main Form.
In the last lines of the function I have put those lines

Form1 lab = new Form1();
lab.pictureBox1.Refresh();
lab.btn2.Text = "grayscale";
lab.button1.Text = "Restore to Grayscale";
lab.button1.Width = 120;

The "button1", "btn2", and "pictureBox1" are all "Modifiers=public" in Form1. The problem isn't there.
When I am running the code, C# decides to ignore those 5 lines for a reason I cannot understand

As I get it, the problem must be in the first line, but cannot fix it. Help me please.