How to choose note and fret on Electric Bass

Hi, I have just got the new Electric Bass VST plugin, but I can’t work out how to make it play specific notes. For example I want to play the D on the fifth fret of the A string, and then the G on the third fret of the E string. I have tried the force string key switch but it doesn’t seem to give consistent results. Sometimes it will play the right note other times it will play the right note but at the wrong fret number.

Could someone please explain how this all works.