Arrows⬆⬇
So some says that use as many less arrows as you can( got from some guides)
But some guides (in forum only) suggested that use arrows on all of your players (for e.g. all red arrows to Midfielders and strikers and blue to all defenders...so I want to ask that which one is correct also is there any advantage/disadvantage of using too many/less arrows.....

Formation
Some says that (in guides) use counter formation according to your opponent (means frequently change in formation) and some says that always keep only one formation and tactics (and some of them claim that they have won also by this)

So I want to ask which one is right
And same here is there any advantage/disadvantage of changing frequently/not changing your formation.....
Thank you