In the General pane of the Preferences dialog box, you can customize settings for everything from playback preroll duration to bin behaviors.
Play a sequence with preroll and postroll pauses
Specify and apply default transitions
Change the default duration for still images
Scroll a sequence during preview
Render audio when rendering video
Scale assets
Change bin behaviors
Optimize rendering for available memory
Specify whether to render audio when rendering video
Set the default keyframe display of video tracks [PH Revise for setting track default] (adobe.com)
Set the default keyframe display of audio tracks [PH revise for setting default] (adobe.com)