Can I upgrade my iPhone from AT&T using the apple store?

I want to upgrade my phone from AT&T. The problem is that they don't have the color I want. The only store who has it is the apple store. Is it possible to purchase the phone through the apple store website and upgrade it online. Or do I have to go to an AT&T store.

My iPhone keeps disconnecting from the Internet, why?

I keep connecting it to the Wi-Fi and then it disconnects. I just got the iPhone 6+ and it never happened with my iPhone 5 or any other product in my house. It works at my cousin's house though. Could this be a problem with my Wi-Fi and not the phone?

Forgotten restrictions code on iPhone 6?

I'm trying to completely wipe my iPhone 6 of all data. I'm trying to do this because i accidentally gave it the same name as my old phone, so when i restored it, it came up with everything that was on my old phone, and my old phone had a restrictions code. My dad put this on my old phone, and he doesn't remember it. To erase all content and settings, you need the answer to the general pass code, (which i knew), and the restrictions pass code. I don't care what i have to do. I want all data erased.

How to get a SIM card for an iPhone 5S?

My dad bought an iPhone 5s from a guy and he didn't ask if it came with a sim card and what company it was because he doesn't know anything about smartphones. I went to the store and they don't sell any and I checked on eBay but I'm pretty sure i need to know what company the phone is. So does anyone know how I can get a SIM card or will I need to tell my dad to ask the guy?

My iPhone time is slow, what can i do?

My iPhone time is slow, what can i do?

Added (1). I tested a possible reason why this is happening, and turned off my iPhone, and then waited 5 minutes, and then turned it back on again, and it was slow by 5 minutes, compared to my macbook time, which is accurate.

Any ideas what to do about this?

I think it started after update 7.1.2 was downloaded and installed, but can't be sure now.