Match Prep. Question

Ive got a newb question concerning match preperation. I had my ass. coach do it up to this point.

So I select the formations I want my players to prepare to use during the match. Lets say a forward gets injured for several games and I change a forward position from advanced forward to target man. Do I have to re-save the tatic every time I make a change like that or is it just if I change the formation from a 4-2-4 to say a 3-3-4? Will my players still have full knowledge of the tatic if I do the subtle change of making a advance forward a target man?

Thanks in advance for any replies.

Changing player roles shouldn't effect match prep I don't think as player roles isn't one of the bars that fill up to fluid over time. Changing things like formation, team width, depth, pace, mentality, creative freedom, marking and closing down will have a negative effect on the ability of your team to play well within your tactic.