try this:
open sources/misc/session.php
find:
PHP:
$check_time = time() - 3600;
change to:
PHP:
$check_time = time() - 86400;
that should give you 24 hour login session, you can adjust the duration as needed. We don't have a hook location for this so it cannot be done via plugin yet, but if you find this works I will add a hook here for upcoming release.