This guide will let you know how to change your in-game formation/custom tactics in FIFA. Go through the guide and follow the step-by-step instructions to change it.
You will first need to go to My Squad and click on the L2 button from the controller to open the squad actions option. From there, you need to tap over to custom tactics. Now you need to press the L2 button again and change your tactics to attacking mode. After that, use your d-pad to select your tactics, and you will be switched over to your custom tactics menu.
To change the formation, you will need to tap on the next tab, Formations. You can choose different formations; once you choose it, you need to press the Triangle button from the controller to equip it. If you want to swap the positions, you have to select the player first from the right side of the screen and choose the player you want to swap with. You will see that they will change their positions.
If you want to check and read the instructions, you have to tap over to the next tab, and you can customize your squad gameplay and set your squad roles from there.