The 4.6 install instructions (like the 4.5 instructions) call for the editing of the /usr/local/nagios/etc/opsview.conf file, to replace the 'changeme' values with the newly selected MySQL root password.
This file no longer contains entries with values 'changeme', which is a minor worry.
A greater worry is that the entries read:
and the /usr/local/nagios/bin/db_mysql script fails when running against that file.
This was an installation on a pristine server from the Opsview repo.