If you want to know what I use in such a situation:

<div *ngIf="isLoggedIn">
<h1>Welcome User</h1>
.....
</div>
<div *ngIf="isForgotPW"> 
<h1>Forgot Password</h1>
.....
</div>

In your .ts file you can define and change values easily.

isLoggedIn = false;
isForgotPW = true;