update 2 dimensional array PHP

I made a 2 dimensional array which checks if 3 of the same values are equal to each other. My problem is that when the code detects 3 in a row it changes values, but it doesn’t update to the original array ($aww_ar).

Is there a way to do this?

Code:

<?php

$aww_ar = array();


echo"<table>";
for($y = 0; $y < 6; $y++){
    echo"<tr>";
    for($x = 0; $x < 6; $x++){
        $randomise = rand(1,4);
        $aww_ar[$x][$y] = "<td>".$randomise."</td>";
        echo $aww_ar[$x][$y];
    }
    echo"</tr>";
}
echo"</table>";


$counter = 0;
for ($h=0; $h <  count($aww_ar); $h++) { 
    for ($u=0; $u <  count($aww_ar[0]); $u++) { 
        if($aww_ar[$h][$u] == $aww_ar[$h][$u-1] && $aww_ar[$h][$u] == $aww_ar[$h][$u+1]){
            $counter++;

            $aww_ar[$h][$u] = 'X';
            $aww_ar[$h][$u+1] = 'X';
            $aww_ar[$h][$u-1] = 'X';
            
            echo $aww_ar[$h][$u];
            echo $aww_ar[$h][$u+1];
            echo $aww_ar[$h][$u-1];        
         }
    }
}
echo $counter;

Answer

Ive worked it out a bit with the help of Lopes Wang

<?php

$aww_ar = array();


// Create array
for($y = 0; $y < 9; $y++){
    for($x = 0; $x < 9; $x++){
        $randomise = rand(1,4);
        $aww_ar[$x][$y] = "<td>".$randomise."</td>";   
    }
}

// Detects matches and marks them with X
foreach ($aww_ar as $key=>&$value) {
    foreach ($aww_ar[0] as $k=>$v) {
        if ($k > 0 && $aww_ar[$key][$k] == $aww_ar[$key][$k - 1] && $aww_ar[$key][$k] == $aww_ar[$key][$k + 1]) {

            $aww_ar[$key][$k] = 'X';
            $aww_ar[$key][$k + 1] = 'X';
            $aww_ar[$key][$k - 1] = 'X';
        }

    }
}

echo"<table border='2px;'>";
for($y = 0; $y < 9; $y++){
    echo"<tr>";
    for($x = 0; $x < 9; $x++){    
        echo "<td>" .$aww_ar[$x][$y]."</td>";
    }
    echo"</tr>";
}
echo"</table>";