Welcome to the forums
You'll get a quicker response to future questions if you post it in the BIAB forum for Windows or Mac. The Tips and Tricks forum is about discoveries that users make that they want to share with the world.
To answer your question ...
If the solo is a Realtrack solo, it cannot be raised an octave since Realtracks are not musical notes; they are pre-recorded sections of performances.
If the solo is a midi solo, have a look at the image below.
Click on "Soloist" on the top menu then "Edit Solist Track" and then "Transpose Soloist Part". For an octave change, "12" will need adding to the top box in the dialogue box that appears. I cannot remember if it needs to be 12 or -12 (one is up an octave and the other is down an octave). If you try it out, it's easy to work out which one is needed.