Paste the Cron Command into the Command Line Interface. At the end of the command, add the following command and options:
all -F -vvv
The all command will execute all the tasks.
The -F option forces all the tasks to be executed, even if some of the daily tasks have already been performed today
The -vvv option sets the output verbosity level to maximum, meaning everything which can be output will be output.
You should now be ready to execute a command similar to:
php -q /home/v71whmcssupport/public_html/whmcs/crons/cron.php all -F -vvv