Premiere Pro Export multiple audio tracks being merged into 1

[Daniel36800706hn6d]

Hi All,

I've got a project where I've brought in 3 audio tracks and synced them all, but I'm expecting them to be written out as 1 mp4 file with 3 audio tracks as choices, but all three are being played as one track.

Any advice on why its writing them all into 1 on export?

Thanks,
Dan