I was supposed to change my formation in the 45th minute. That happened but now I change my formation at least twice every minute.

(50 min) Sparta Nijkerk
Formation changed by Sparta Nijkerk. They will play 5-1 attack and 5-1 defense. Players on the field are Dillan Kaper, Robbe Jacobsen, Marinus Kempton, Mitchel Peeters, Xander Aelbrechts, Erik Belevander and Erik Mul.

(50 min) Sparta Nijkerk
Sparta Nijkerk decided to change their formation. Dillan Kaper, Robbe Jacobsen, Marinus Kempton, Mitchel Peeters, Xander Aelbrechts, Erik Belevander and Erik Mul are in the game. They will play 5-1 attack and 6-0 defense.

(50 min) Sparta Nijkerk
Sparta Nijkerk will change their formation. Dillan Kaper is in the goal and the outfield players are: Robbe Jacobsen, Marinus Kempton, Mitchel Peeters, Xander Aelbrechts, Erik Belevander and Erik Mul. They will play 5-1 in attack and 5-1 in defense.

(50 min) Sparta Nijkerk
New players coming on court for Sparta Nijkerk. Dillan Kaper, Robbe Jacobsen, Marinus Kempton, Mitchel Peeters, Xander Aelbrechts, Erik Belevander and Erik Mul. They will play 5-1 attack and 6-0 defense.

i set on today's friendly new tactics on 20th and 4oth minutes, on 20 it was changed, but on 40 not

If you put (20+ minute / any score) for formation 1 and (40+ minute / any score) for formation 2 then the switch won't be made. Computer looks for the first formation that fits the conditions and puts that formation on court - or not if the formation is already on court, like in your case.
If the two conditions would be separate then we would again get the case of formation switch every attack (first formation 2 would fit the conditions in 41st minute, then formation 1 in 42nd, and so on and so on).
I hope you understand what I'm trying to explain. Remember, it's 20+ (twenty plus ) minute on conditions, not 20.

@Admins: Thanks for making this clear - i assumed, that when 40+ Minute is reached, it would switch to Formation 2 - so, another learning.

I dont want to ask why it is programmed this way - i take it as given for the moment.

So but maybe you please make clear, how the second condition works:
Setting for the Game:
-> Starting Formation: Winning by 1-2 Goals at -
-> Formation 1: Winning by 5-6 Goals at -
-> No other Formations or conditions set!

Game progress:
-> Game starts: by starting the game, i assume that Starting Formation will play, although there is no lead - right?

-> Game ongoing - take an early lead, expand lead to 3 -> which Formation will be played?

-> Game is ongoing - expand the lead to 5 -> which formation will be played?

-> Game still ongoing - players go crazy, expand the lead to 9 -> which formation will be played?

-> Relax factor comes into game, my players are exhausted, by the end of the game the lead collapses to only 3 goals -> which formation will be played?

Thank you in advance!