I've rarely ever used Illustrator as it's not usually required of me.
But I need to change the color in a logo file to a different color. This logo file has tons of layers to it so I don't want to change each layer to the new color one by one. What is a more efficient way of changing just one color to another color? Please note again that the Illustrator interface is all rather new to me as I'm used to Photoshop. Thanks for your help in advance.
From "Select" menu choose "Same->Fill Color".
After changing the color, you can drag it into the Swatch palette and tick the "Global" button. This way if you change the swatch, all this particular color instances will be updated.