Denon AVR-2113CI Owner's Manual page 130

Setup Lock
Protect settings from inadvertent change.
Setting items
On : Turn protection on.
Lock
Off : Turn protection off.
When canceling the setting, set "Lock" to "Off".
NOTE
When "Lock" is set to "On", the settings listed below can no longer be
changed. Also, "SETUP LOCKED!" is displayed if you attempt to operate
related settings.
• Setup menu operations
DVD
General
Default settings are underlined.
Setting details
• Levels
127