Are unticked boxes in the tactics screen active?

At first this seems like a stupid question, because if a box is unticked it should mean that the action is not selected, but in the case of corners and free kicks, if you leave the boxes unticked the players still do what the boxes say. (attack near post, attack far post, etc)

Then in the Tactics forum some people say that if the playmaker box is unticked, even if there is a player in the box, the team will not use him as a playmaker.

Anybody knows for sure how this works?

As far as I know, the people in the tactics forum are incorrect. If a box is unticked, it means that you are using the default value that the tactics creator has assigned. By ticking a box and changing a value you are overriding the default setting.

So in the playmaker example, if you have a player set up in the role Deep-lying Playmaker or Advanced Playmaker, he will automatically be assigned as the team's playmaker in the team instructions. If you do not have a player with a playmaking role set, the team will have no-one set as playmaker in the team instructions. And if you want to set a different player as the team's playmaker (such as a ball-playing defender), you would tick the box and select him.

Does that make sense? That's how it's supposed to work, anyway.

That's what I thought and it makes sense to me, but since there were different opinions I don't know for sure how it works.

Im sure i read in the forums a few additions back that playmakers are only used if the option is ticked?

It automatically chooses a playmaker for your team so if what i believe is not the case then it would mean it is flawed because their would be no way of not picking a playmaker for those who dont wish to use them?

EDIT: Also it assigns mine as the Trequartista and not the advanced playmaker.

It does, you can tick the box and choose "none".