... how do I substitute the $resultarray[3] values from 0 to 1 instead of doing at @resultarray?

One way:

>perl -wMstrict -le
"use Data::Dump;
 ;;
 my @resultarray = (0, 0, 0, 0, 0, 0);
 dd \@resultarray;
 ;;
 $resultarray[3] =~ s/^0$/1/;
 dd \@resultarray;
"
[0, 0, 0, 0, 0, 0]

[0, 0, 0, 1, 0, 0]
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