Tell Handbrake to leave audio alone

[Knocks]

I am converting a 1920x1080 video to 720p with Handbrake, and it keeps adding an extra audio track to the final result, which seems to be a downmix of the original AC3 6 Surround track to AC3 stereo. I can't seem to find the option not to convert the audio. Why is it doing that by default, and how do I change this setting?

[poisondeathray]

In the audio tab, under "audio codec" set it to "AC3 passthru"