So you have an array of arrays (2 dimensional) built with

husani|10|20
bill|1|3
john|5|2
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That gives you something like @array[][]. husani is at $array[0][0] and bill is at $array[1][0]. You must loop through the first dimension while checking the appropriate index in the 2nd dimension. When the match is found you can change any element in the 2nd dimension.

for (my $x = 0; $x < @array; $x+) {
  if ($array[$x][0] eq 'bill') {
    $array[$x][1] = 45;
  }
}
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It may not be the slickest way to do it but it will work.