goofeyfoot,

I got caught with this until I found out about the freeze function, but even then sometimes I forgot to freeze.

Luckily another way was introduced a few versions back.

Go to; Edit / Copy Special / Copy/Move Tracks.

This will allow you to copy tracks from one source to another, so in your case you could copy the Bass to the Melody or Solo Track then mute the Bass track.
The midi channel for the Bass track is ch2 but I usually leave all selected.
When the Bass copies to the Melody or Solo track the notes will visually be an octave lower, this is correct. As far as I'm aware the true Bass track has been configured so that the notes don't sit too far below the bass clef, hope this makes sense.

Anyway, I find doing it this way allows more scope for editing without the need to freeze. For example, if after editing I need to change key, this cannot be done to a frozen track, but the Melody or Solo track will change as normal.
Hope this is of use to you.

regards
Vintage