In the "Legacy sequence audio" drop-down list choose one of the following options:

  • Nothing – the individual master audio track is created for each audio track on Timeline:

Compatibility_option_nothing
  • Mix-down into S1 – all Timeline audio tracks are mixed into one master audio track:

Compatibility_option_S1
  • Mix-down into S1 and S2 – the first two timeline audio tracks are mixed into the first master output track; all other audio tracks are mixed into the second master output track:

Compatibility_option_S1_S2