Elements within an array may be changed by assigning a new value to a specific index, for example:

$myArray = 1, 2, 9, 4, 5 
$myArray[2] = 3 

Values in an array may be changed within a loop, as follows:

$myArray = 1, 2, 3, 4, 5 
for ($i = 0; $i -lt $myArray.Count; $i++) {
     $myArray[$i] = 9 
}