IPhone Wi-Fi connection trouble?

My iPhone can't keep a connection to my house's Wi-Fi for more than a few minutes before disconnecting. It seems like it disconnects whenever I try to watch YouTube videos on it. However, on my computer or video game system, I do not disconnect from the Wi-Fi ever. How do I fix this problem?
I have an iPhone 6s

ICloud for IOS 6 on iPhone 4?

What happens if I turn everything off on my iCloud? What exactly is iCloud? I don't want anyone else besides me to get access to it but I'm not deleting my account.

I can't export imovie videos from my mac to iphone?

I made a video on iMovie on my Macbook, and I saved it to the theatre. I then saved it as a file onto my Mac and it worked perfectly good. I tried to airdrop it to my iphone, and it airdropped but the video I received was plain white and wouldn't play. I sent it to my ipad and other devices but nothing worked. Then i saved the movie as a file again onto my usb. It worked on the usb great when it was plugged into my mac, but on my samsung laptop, it would show a black screen and only play the audio! Is it the format? Did I download it wrong? I really need to get it onto a usb or my phone as soon as possible because it is a school project!

Third party iPhone charger? How fast can it cause damage?

I have always known using third party no name iPhone chargers can wreck your iPhone and stop it from charging properly, so I avoided. But I plugged my iPhone into my friends charger which I realized after was not an apple charger, it was only plugged in for 5-10 minutes before I removed it- could it possibly have already done some damage to my phone? I can't tell if my phone is charging slower or if I'm worrying myself over nothing!

Is there a solution to this iPhone problem?

Is there a solution to this iPhone problem?

Added (1). I dropped my iPhone not too long ago and, as many people complain, I'm now having problems with it. It opens for the first split second with the normal colors, but then fades out to complete green and then the color goes black without dimming first (although it doesn't appear to be restarting). Additionally, there are white blocks on the upper part of the screen. I read one webpage that suggested tapping or slapping the back, I've tried it and it did get a little better.