How to Remove All Personal Data On My Iphone?

I want to sell my Apple iPhone 4s on ebay but i don't want to reset it because I want to keep an app on it to sell however i don't want to remove everything but i want to get rid of all my personal data eg. Phone numbers, passwords, accounts and ID's. All i want left is my iPhone with an app on it with none of my info. Also, if i get rid of/disable my game center account, will this remove my app. Please don't give stupid, meaningless answers, thanks!

Added (1). If i back it up on my laptop, then reset my iphone. Can i get back my app by downloading it back onto my phone? I don't want to loose flappy birds!

Added (2). Right, -.- the app has been deleted from the app store and is rare and no longer available. If you read what i wrote then it might make sense

Added (3).… If i deleted all data off my phone without resetting, would whoever bought it be able to get my personal info, of anything that was removed back?

Why aren't I receiving emergency alerts?

I have an iphone and it has snowed in our area heavily. In my settings, the emergency/ government alerts are turned on. I didn't receive the alert, but luckily my brother did. Why didn't I get them?

What is a 'piece of technology'?

My uni essay question for 'American Studies' is:

"Pick one piece of technology and show how it has influenced American development."

Would it be acceptable to write the essay about Apple. Inc, mainly focusing around the iPhone? That's considered a "piece of technology" and there's a lot to write about it surely, right?

My iMessages only send if I have Wi-Fi?

I have an iPhone 4S and on Sunday I tried to send a text message (it was an iMessage because the other person had an iPhone) but it turned it into a text message and still wouldn't send. I've never had a problem with this before Sunday, and it's really annoying me. I've always been able to send iMessages without Wi-Fi and regular text messages, too. Does anyone know what's wrong or how I could fix this?

Added (1). My mobile date works fine with everything else (apps, safari, ect. Work fine without Wi-Fi), and I don't believe it's my friends' phones because I've tried to text at least five different people and it doesn't work.

Added (2). I turned it off and then back on and it worked again.

Should I sell my Iphone with Flappy Bird on Ebay?

Because of the recent closure on Flappy Bird, I'm thinking of selling my Iphone 5c (16gb) with Flappy Bird on Ebay for £500. Would I get someone to buy it or not? Furthermore, Should I sell my iphone as many of the bidders on ebay are bots or just fake.

Walking Dead Mid Season Premier?

Is there anywhere I can stream The new premier of The Walking Dead Season 4 Episode 9 on iPhone 5 for free? * fingers crossed*

Creative things to say in gaming video intros & outros?

Mmk so I have this gaming channel, and I just started. So I'm thinking about doing a voice over since I don't have a mic or an earphone with a built in mic; I'll just record it on my iPhone. Anyways, I need creative ways to start my videos and end my videos. Like how Pewdiepie does that funny intro, and how Joey Graceffa ends his video by saying "May the odds be ever in your favor, goooooooooodbye!"

I want a creative one like those, or at least give me ideas.

Will my iphone lock to my sim card?

Hi, I bought the iphone 4 16GB second hand so it had already been used and had already had a sim in it and was locked to that but the seller managed to unlock and then sold it to me. I was wondering seeing as it has already been unlocked once when I put my Vodafone sim card into it will it lock to that carrier or remain unlocked allowing me to use another carrier such as Orange or T-Mobile?