I want to update a page, but i use special characters like ç/ã/á - php

Question

It is correctly printing in UTF-8_encode(), but after i update it , cause i have a button to update the database, it prints with some stupid characters...
I have it on the database in a table, and when i list it on a page and then change something and update it to the database it print with stupid characters
Code where i update:
<?php
if (!isset($_SESSION["auth"])) {
header('Location: index.php?backUrl='.$_SERVER['PHP_SELF']);
exit();
}
$host="localhost"; // Nome do host onde esta o banco de dados. Padrão ‘localhost’
$usuario="root"; // Usuário do Mysql. Padrão ‘root
$senha=""; // Senha do Mysql
$db ="teste"; // Nome da Database
?>
<meta charset="utf-8"/>
<h2 align="center" style="color:white; font-family:"Trebuchet MS", Helvetica, sans-serif; font-size:20px;">Alteração de Orgãos</h2>
<form action="" method="POST" name="alt" id="alt" enctype="multipart/form-data">
<div class="box">
<label>
<textarea rows="20" cols="100" id="texto" name="texto"><?php
$mysqli = mysqli_connect("$host", "$usuario", "$senha")or die("cannot connect");
mysqli_select_db($mysqli,$db)or die("cannot select DB");
$query2 = "Select * from teste";
$stat=$mysqli->query($query2);
if($stat->num_rows>0)
{
while ($row = $stat->fetch_assoc()) {
echo utf8_encode($row["texto"]);
}
} else
{
echo utf8_encode("Não existe nada na página");
}
?></textarea>
</label>
<label >
<input align="center" type="submit" value="Alterar" name="alterar_btn" id="alterar_btn" class="entrar">
</label>
</div>
</form>
<?php
$a1=$b1=$c1=$d1='';
//Alterar
if(isset($_POST['texto']))
{
if(isset($_POST['alterar_btn']))
{
$query="update teste set texto=? where titulo='orgaos'";
$stat = $mysqli->prepare($query);
$stat->bind_param('s',$_POST['texto']);
if ($stat->execute() && $stat->affected_rows>0){
echo "<div><strong>Foi alterado um Orgão!</strong></div>";
}
else{
echo "<div><strong>Nao foi alterado!</strong></div>";
}
$stat->close();
}
}
?>