Q:

How can i store the registration details in local storage without overwriting it the next time? 

So basically i have a registration form and everytime the user registers, i store their data in HTML local storage, but i want the data to look like this for example:
user| [{"username":"Maximillian","password":"whatever","address":""whatever".... and so on.  So far i have this code but i am confused with why it doesn't work the way i want it to.  And how do i make sure that when another person registers, their details does not overwrite the current register details already on local storage? 

A:

You could store an array of the users.  For example:
var users = JSON.parse(localStorage.getItem('Users')) || [];
var userData = [{Username:document.getElementById("UserName").value},
{Email:document.getElementById("EmailAddress").value},
{Password:document.getElementById("PassWord").value},
{Address:document.getElementById("Address1").value},
{Phone:document.getElementById("PhoneNumber").value}];

users.push(userData);
localStorage.setItem('Users', JSON.stringify(users));

Then access the users as such:
var users = JSON.parse(localStorage.getItem('Users')) || [];
users.forEach(console.log);
users[0];
users[1];
[etc.]