Recovering the id from session in the other modules would just be redundant

If you add a subroutine into manageusers.pm like this

sub getLoggedOn_user_id {
  my ($dbh,$query) = @_;
  my $session = CGI::Session->load(
    "driver:MySQL", $query, { Handle => $dbh } 
  );
  return $session->param("user_id");
}
[download]

then only change in your script is from

$userid_1 = $manageusers::LoggedOn_user_id;

to

$userid_1 = manageusers::getLoggedOn_user_id($dbh,$q);

One less 'global' to worry about

poj