How to UPDATE from MySQL where Table name is a variable

Question

I want to update a table where the table name is a variable. I can update the table just fine but when I try and make it a variable I get problems. I probably just don't know the syntax very well.

if ($_SERVER['REQUEST_METHOD'] == 'POST'){

$table = "settings";

    $tr_title = $_POST['tr_title'];
    $tr_slogan = $_POST['tr_slogan'];
    $tr_signin = $_POST['tr_signin'];
    $tr_makeacall = $_POST['tr_makeacall'];

$statment = $connect->prepare(
    'UPDATE $table SET
    tr_title = :tr_title,
    tr_slogan = :tr_slogan,
    tr_signin = :tr_signin,
    tr_makeacall = :tr_makeacall
    ');

    $statment->execute(array(
        ':tr_title' => $tr_title,
        ':tr_slogan' => $tr_slogan,
        ':tr_signin' => $tr_signin,
        ':tr_makeacall' => $tr_makeacall
        ));

    header('Location: ' . $_SERVER['HTTP_REFERER']);

}

I also tried doing an escape_string

$table = "settings";
$table = $mysqli->real_escape_string($table);

I'm pretty sure my syntax is just off.