How to find and replace specific value in multiple array

Question

I want to find flag key from array and replace new value. for example if i found flag values == 2 then i'll put new value instead of old.

Following is my array.

Array
(
    [0] => Array
        (
            [id] => 863
            [flag] => 1
            [qty] => 2
            [size] => 8
            [fly_name] => Bead Headed Prince Nymphs size 18
        )

    [1] => Array
        (
            [id] => 861
            [flag] => 1
            [qty] => 2
            [size] => 8
            [fly_name] => Bead Headed Prince Nymphs size 14
        )

    [2] => Array
        (
            [id] => 671
            [flag] => 1
            [qty] => 4
            [size] => 8
            [fly_name] => Royal Wulff size 12
        )

    [3] => Array
        (
            [id] => 661
            [flag] => 1
            [qty] => 2
            [size] => 3
            [fly_name] => Hare's Ear Tan size 16
        )
)

I want to find if flag key == 2 then replace new value of flag key , i have tried following way but not work.

if(in_array(2, $fliesUserColumn)) { // search value in the array
    foreach($fliesUserColumn as $key => $val)
    {
            if ($val == '2') $fliesUserColumn[$key] = 'search4';
            }
    }else{
            echo "not";
    }
        echo "<pre>";
        print_r ($flyOfStores);
        echo "</pre>";
    die;

And out put like with new values in array

Array
(
    [0] => Array
        (
            [id] => 863
            [flag] => newvalue
            [qty] => 2
            [size] => 8
            [fly_name] => Bead Headed Prince Nymphs size 18
        )

    [1] => Array
        (
            [id] => 861
            [flag] => newvalue
            [qty] => 2
            [size] => 8
            [fly_name] => Bead Headed Prince Nymphs size 14
        )
   ...

)

Answer 1

Try below example

foreach ($fliesUserColumn as $key => $val) {
        if ($fliesUserColumn[$key]['flag'] == '2') {
            $fliesUserColumn[$key]['flag'] = 'Newvalue';
       } 
}

Answer 2

Try this

    foreach ($fliesUserColumn as $key => $val) {
        if ($fliesUserColumn[$key]['flag'] == '2') {
            $fliesUserColumn[$key] = 'search4';
        } else {
                echo "not";
        }
    }