This is happening because the special var $_ is referring to the array element received in a particular for loop. What you really want is an array of 4-element arrays for the buttons. Then you can have a foreach inside another foreach...

foreach my $thesebuttons (@aoa) {
  my @b = @$thesebuttons;
  foreach my $thisbutton (@b) {
    code for printing out this button...
  }
}
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