Read By / Acknowledged

Hi There,


Part of my app has a memo system. What I would like to be able to do is send these memos to a set group of staff chosen from a department drop-down and then for it to display a list of which staff it appears to. I would then like the staff to be able to click 'read and understood' and it to be logged. This I have been able to do using a trigger action of inserting a new record into another table called 'Read & Understood' however, I cannot get the trigger option to go away once they have read it and equally I cannot see who has not read it, only the people that have click confirmed and understood?


Hope that makes sense? I seem to be going round in circles.