Right click on the surround diagram and select "LFE only" for the LFE track. Make sure that in each surround channel, when you have dragged the small diamond shape to the desired speaker (in the small diagram) that you click on the other speakers in each diagram to mute these channels for each track or you will get channel bleed though in your mix.

Youdon't have all the tracks, including the sync track, highlighted when you try to mute the track do you? And you're not trying to mute the tracks in the mixer section are you? You only need to click the mute icon next to the track you want to mute.

If the track sounded like chipmunks when you changed the fps in Besweet then you had sped it up and not slowed it down. Did you use besweets built in 25 >23.976fps conversion preset?