Hi Danna,
I have been playing around with BIAB and, from what I've discovered, I suspect that your problem has arisen because you have loaded in a MIDI file via the "File" menu and the Melody track has automatically been set to "Multi(16)-channel".
The easiest way around this is to use the "Import melody from MIDI file" by following the #1, #2, #3 in the image below.

To import this Melody, you'll need to know which track it has been assigned to by your notation software (it's probably channel 1).
After you select your MIDI file, the below dialogue box will pop up. Make sure that all channels other than the one that the melody is on are unchecked. Click OK

Now you need to set the Melody track-type to Single Channel by following the #1, #2, #3 below.

Once this is done, the Lead Sheet Options should be working properly.
Hope this helps,
Noel