What are Expert and Installer modes?

Expert and Installer are two modes to configure an ISP or a PA, accessible through the "Expert Setup" button in the WebUI at startup. There is a different password for each.

The default password for the Installer mode is “installer”.
The default password for the Expert mode is “expert”.

You can change both in the Installer mode and reset Installer and Expert passwords to default.

Installer can manage every setting: System, Input, Main Speakers, Settings, Presets, Monitoring, Firmware Upgrade and Factory Reset. The Installer mode can enable/disable access to any of these settings in the Expert mode. In this way, Installer can allow a sub-level of configuration to the Expert mode.
By default, Expert only has access to "System", allowing for log export, configuration backup and restore.