I'm trying to make a Keep Out sign, so i made the wooden material with the appropriate texture and I wanted to add the writing using another texture with a transparent background. The problem is that when I do that the second texture ends up on all the other faces of the model too, even though I did another unwrap with only the face I want the writing on, is there something I'm forgetting? I'm including also a screenshot of the nodes I made. The three wooden planks are separated object, my plan was to put a part of the writing on each plank and then align them moving the UV on the UV editor.
EDIT: the links provided by Mr Zak did solve my problem so I want to thank him for his help.