How do I change the path of the "ASP.NET_sessionid" cookie?

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C#

ASP.NET

I want to change Path attribute of ASP.NET_SessionId in my web application.
I am trying to change the path of the ASP.NET_SessionId cookie in Global.asax's Session_Start event as below.

HttpContext.Current.Response.Cookies["ASP.NET_SessionId"].Path = "/MyApp";

When I check the application in crome , 2 cookies are being created (here are the headers):

Set-Cookie: ASP.NET_SessionId=; path=/MyApp/
Set-Cookie: ASP.NET_SessionId=qwtixezaxnrexxvvdjdg5jje; path=/; HttpOnly 

What I have tried:

HttpContext.Current.Response.Cookies["ASP.NET_SessionId"].Path = "/MyApp";