_WHITE_KNIGHT has covered most of your questions - the only missing piece is that this is a one-time thing.
If you select someone in your party/raid and press 'F' then you will target the same person they are currently targeting.
If they change targets then you will need to repeat the process.
Also, the people who reply here are almost all volunteers. As it is over a day since you posted initially, it's possible that your question was overlooked. Nevertheless the sarcasm isn't really necessary.
you are right, i was a bit impatient. Thank you for the replies.
Oh i tried to do that just like you said and even tried some variations of it and i could not get it to work. I guess this is another thing broken in game?