Question

The 3 forms allow access as member, guest or then as newly registered.
However if someone clicks on the lower part of the form it automatically sends the cursor to the top part.

<form action="schlogin.php" method="post">
  <fieldset>
    <legend>Member's Login</legend>
    <label for="username">Username: 
        <input type="text" name="username" id="username" value=""/>
    </label>
    </br>
    <label for="password">Password: 
        <input type="password" name="password" id="password"/>
    </label>
    </br>
    <input type="submit" name="login" class="loginButtons" value="login"/>
    </label>
    </br>
  </fieldset>
</form>

<form action="schlogin.php" method="POST">
  <fieldset>
    <legend>Guest Player</legend>
    <input type="submit" name="guest" class="loginButtons" value="Play as GUEST!" />
    </label>
    </br>
  </fieldset>
</form>

<form action="schlogin.php" method="POST">
  <fieldset>
    <legend>FAST Register</legend>
    <label for="username">Username: 
        <input type="text" name="username" id="username" value =""/>
    </label>
    </br>
    <label for="password">Password: 
        <input type="password" name="password" id="password"/>
    </label>
    </br>
    <label for="email">E-mail:
        <input type="text" name="email" value=""/>
    </label>
    </br>
    <input type="submit" name="register" class="loginButtons" value="I WANT TO PLAY TOO!"/>
    </label>
    </br> 

    I've forgotten my password:
    <input type="submit" name="forgotten" class="loginButtons" value="Send me a new password!"/>
    </label>
    </br>
  </fieldset>
</form>

Answer 1

In your second form change

<label for="username">Username: 
<input type="text" name="username" id="username" value ="<?php if (isset($username)){echo $username; }?>"/></label></br>

to:

<label for="register_username">Username: 
<input type="text" name="username" id="register_username" value ="<?php if (isset($username)){echo $username; }?>"/></label></br>

or whatever you like.

The point is that the id for every html element should always be unique. And the label element’s for attribute should match it’s associated input element’s id attribute.