my %regular_hash = (
    question1 => 'How are you?',
    question2 => 'What is your name',
);

print $regular_hash{question1}; # prints 'How are you?'

change_question1(%regular_hash);

print $regular_hash{question1}; # still prints 'How are you?'

sub change_question1
{
    my %regular_hash = @_;
    $regular_hash{question1} = 'What is your mothers name?';
}