Today, after 10 months of relatively trouble free S4 usage, my phone decided to show Central Time instead of Mountain Time. I found where others had this problem and I took out the SIM card and battery, restarted without WiFi, and it did not correct. I restarted in safe mode, and it did not correct. Finally, I put it in airplane mode and back to normal, so it is working again for the moment. I rely on my phone for my alarm clock and I can't have it switching to the wrong time whenever it feels like it. What the heck?? If others have this problem, it is a software issue and it needs to be corrected. Thoughts anyone?