Writing tracks with different instruments

I am a new user. I did attempt to read the manual and search the forum to figure this out but still cannot for the life of me get this right. If I pull up the mix tab in hookpad plus, I can see where I have different instruments. However, I cannot get my staffs to actually program anything other than lead and chord section. How do I switch to where I am only programming the bassline for the song as opposed to lead and chords?

You can’t enter a bassline in Hookpad, at least not currently. The bass instruments in the mix panel just play the bass of the chord.