my $hash_rev = {   #notice the change of opening brace
    question1 => 'How are you?',
    question2 => 'What is your name',
};  # and the corresponding close

# and slightly different access methods
print $hash_ref->{question1}; # prints 'How are you?'

change_question1($hash_ref);

print $hash_ref->{question1}; # now prints 'What is your mothers name?'

sub change_question1
{
    my $hash_ref = shift @_;
    $hash_ref->{question1} = 'What is your mothers name?';
}