When Arnold is the currently selected renderer in CINEMA 4D, the Render Settings dialog will give access to Arnold settings.
These are global settings which control the behavior of Arnold rendering throughout the scene (there are also per-object settings, accessed via the Attribute Manager).
To access the Render Settings, either click the Render Settings window icon or choose Render > Edit Render Settings.
Change the Renderer to Arnold Renderer.
The Main tab provides access to the parameters that control render quality, lights, textures, etc.
The System tab provides general system-wide controls, e.g search paths, licensing, etc.
The AOVs tab allows you to select Arbitrary Output Variables (passes).
The Diagnostics tab helps you monitor, troubleshoot and optimize your Arnold renders.