Is it possible in the Score/Layout section to change the tablature so that it will not show open strings.
Cubase automatically write the bass note “D” as an open 2.string with a “0 finger”. Most bass players don’t play with open strings. I would prefer the note “D” as a 3. string with a “5th finger”.
But can you chance that?
There’s no automatic way to do that, but all you have to do (for any note) is to right-click on the note, and select the option “Move to String…”
Tip 
…
If you want to change the string for every instance of the same note, select the first instance of the note, then, Edit menu>Select>“Equal Pitch - same Octave” 
. when you then right-click on one of the selected notes, it will work on all selected notes (I haven’t checked… you might have to do that once per page)
A second way to do this is to switch on “Midi Channel 1-6” in Score Settings>Tablature tab.
Then you can control which string the note appears on by changing the MIDI channel. This means you can do the edit Vic described in the Key Editor by shift-double clicking, and setting the channel.
It’s a matter of taste and how you work in Cubase, but of course my method is better. 