In my settings I changed the color to my sim card so I'm wondering if I should change it back because I really don't know what it does can someone tell me
Do you have a dual SIM device? You may also be able to change the name of the SIM card as well. It is simply a way to quickly look at your device and see which SIM is in use. "Oh my SIM is green, I'm using my Mobile Plus SIM. Now it's blue, my Nation Wireless SIM."