Submitting ajax form displays all php isset statements

I'm using following code to send the form through ajax

<script>
     $(document).ready(function(){
     $("#update-settings").submit(function(e) {

var url = "files/jquery-pages/page_jquery_settings.php"; // the script where you handle the form input.

$.ajax({
       type: "POST",
       url: url,
       data: $("#update-settings").serialize(), // serializes the form's elements.
       success: function(data)
       {
           $("#success-settings").hide().html(data).fadeIn('slow');
       }
     });

e.preventDefault(); // avoid to execute the actual submit of the form.
});
});
</script>


<div id="success-settings">
</div>

and this is working fine so far.

My php page is loking like this:

<?php


    if(isset($_POST['change_password']) == $settings_btn_change_password) 
    {       
        echo "The password has been changed";

    }

    if(isset($_POST['update_email']) == $settings_btn_update_email) 
    {       
        echo "This is email update";

    }

?>

The problem is when i hit Submit button change_password example it´s displaying both "The password has been changed" and "This is email update".

I just want to show "The password has been changed" if I have hit that button.

Any ideas why?

Cheerz :)