First - you don't need the system every tick condition in event 5 and 6, for they will be evaluated every tick regardless..
Second - you are picking the nearest talk every tick, which is why the bubble moves..
I guess adding an instance variable to the triangle "TalkUID" would do the trick..
add a triangle set "TalkUID" to talk.UID to the on space bar pressed - event
and replace the pick nearest talk condition in the events below to pick talk by comparison : talk.uid = triangle.TalkUID