How to navigate to second winform from 3rd winform wth Back btn

Question

I have three windows form with same CS name like Collateral Welcome.cs

Now  I implemented one Back button in 3rd screen, as per business requirement it must go to 2nd screen but where as I am to navigate it to 1st screen.I am really confused how to implement this.

 

private void btnBack_Click(object sender, EventArgs e)

{

this.Hide();

CollateralWelcome CW = new CollateralWelcome();

CW.Show();

}

every time it is navigating to 1st screen as given below

 

but it should navigate to 

 

(2nd Screen)

 

I am using back button from 3rd Screen as given below

 

(3rd SCreen)

 

Please help me for this how to achieve back func from 3rd screen to only 2nd screen