#!/usr/bin/perl

use 5.010;

use strict;
use warnings;

use YAML;

sub foo {
    my $array = shift;
    local $array->[0][1] = "bar";
    print Dump $array;
}

my @array = ([1, 2, 3], [4, 5, 6],);
foo \@array;
print Dump \@array;

__END__
---
-
  - 1
  - bar
  - 3
-
  - 4
  - 5
  - 6
---
-
  - 1
  - 2
  - 3
-
  - 4
  - 5
  - 6