Why does my phone only charge when it's turned off?

I have an iPhone 6s. My phone only charges when it's completely shut off, and even then extremely slowly. I've tried different chargers and I don't think that s it. When it's on and I plug it in the lightning bolt doesn't show up and the percentage fluctuates a lot.

Can a outdated iphone ruin a charger?

Recently my boyfriend and i both got a new iphone. Which i was excited about for my battery life to be better. Its been about a month since i got it and my battery life if horriabe still, remind you it's a iphone 8. My aunt has a iphone 5 and constantly used my charger. Is it possible since her phone is much older that is can ruin my charger? My boyfriend battery is perfect but mine drains so fast! I know it might sound dumb but i feel like it can be true?

IPhone 7 Plus not connecting to LTE only 3G?

I just got my iPhone 7 Plus. I upgraded from the iPhone 6. My iPhone 6 worked great in my home. But this iPhone 7 doesn't. Same carriers. I've done the service update by dialing ##873283# but it hasn't worked. I also reset my network settings and that did not work. I also reset all my settings and it still isn't working. Everyone else's phones work in my area except mine. I've called customer service took it to the carrier store, called apple, been to apple. No one knows what's going on. But it's only in my area. I called and asked were there service outages or anything in my area. There are none. Has anybody else had this problem with their iPhone 7 Plus? I only had it since June 5th. My iPhone 6 before I switched was working just fine. I'm with boost mobile (Sprint tower).

Is there a way to find out an iTunes password with an iPhone?

So I have the iPhone with Touch ID, so I'm able to log into iTunes there. I don't have access to my email so I can't reset the password. Is there a keychain or something on the phone that can tell me my iTunes password with just my Touch ID?