Question about Coockies and FormsAuthentication

 Hi all,
In my project I`m working with forms authentication for the user login
and I create a coockies for the user with he check the 'Remember me' CheckBox, The coockies will be expired after 1 day (for example)
But when he come back after little hours I can access the coockies but if used the User.Identity.IsAuthenticated it will return false!!
So,
1- I want the FormsAuthentication be related to the coockies I create, and just expire when the coockie is expired...How to do that ?
2- If the User didn`t check on the Remember Me checkbox I want to him to be authenticated and his authentication expires only when he close my website.. How Can I do that ?

 Thanks
...