A red light on below one of the fuses means the fuse is open on a circuit that is switched on, like light circuit with the wall switch turned on. On our panel, the red lights are not directly below the fuses, but offset a bit, so make sure you are checking the correct fuse. There might be a short causing the fuse to blow, or you may have just overloaded that circuit. It is also possible that when replacing a fuse on a circuit that is shorted, that the fuse can blow when installing it and you might not notice it.
Bob & Becky
2012 Chevy 2500HD D/A CC 4WD