Do not allow preferences to be changed
Supported on: Firefox 76 or later, Firefox 68.8 ESR or later
Registry
HKLM
Software\Policies\Mozilla\Firefox\Permissions\Autoplay HKCU
Software\Policies\Mozilla\Firefox\Permissions\Autoplay Value name: Locked
Enabled: Locked = 1
Disabled: Locked = 0
Description
If this policy is enabled, autoplay preferences cannot be changed by the user. If this policy is disabled or not configured, the user can change autoplay preferences.