My iPhone has moved videos around camera roll and deleted pictures itself?

My iPhone is always telling me I'm running low on storage, I have a few thousand photos and videos. Today I looked at my camera roll and a couple of videos I took months ago have been moved down my camera roll along with the photos I took today. I also noticed a few photos I took last month have been deleted and are in my recently deleted folder. No one used my phone or has access to my apple account so this isn't a case of someone else doing it. Is my phone acting up because it's so full? Can anyone tell me what's happening?

Added (1). My iPhone hasn't got the latest software and I don't have Icloud logged in.

What just happened on my phone?

(excuse my english) so i was scrolling through instagram, browsing memes as usual, when suddenly a pop up appears only for a brief second and all i could read was "screen recording" there were two choices to pick from but i can't remember if they were literally just empty boxes or not since the pop up disappeared really fast, like after a second or so. I hadnt clicked on anything weird, all i did was scroll. Is this a hidden feature or a glitch or what? I have an iphone 6s, if that helps. Am i just being dumb?

IPhone 6 won't turn on or charge

I bought an iPhone 6 today from a shopkeeper I know, he is trust.worthy and would never sell something bad or wrong, i got the iPhone 6 16 GB and I checked it all in the shop and it was fine with IOS 11.2.1 i was in the car and connected the Wi-fi and started using it and suddenly it got slow and got stuck I started pressing the buttons adn suddenly the apple logo apperared and the logo restarted several times then it turned off and I came home tried charging it, nothing appears or happens, i did that reboot or reset with home and lock button, nothing works even connecting it to the laptop it does nt recognize anything.
TRIED MANY THING
Tell me what's wrong and any quick solution!

Why isn't there more space on iPhone after purchasing the extra GB?

Last month I purchased an extra 50 GB for my storage. The money is being taken out but there's still no space. The settings shows that I have 48 GB available but I still can't take pics or download apps. Any suggestions?

How do i change an old name from my used iphone 5c?

I bought my daughter a used iphone 5c! It works great. But when she calls people, its the persons who used to have the phone who pops up? How do i put the phone in my daughters name so when she calls people, its shows up HER name, not the old owners? Its an ATT phone!

How Do I access root files on iOS 11?

I got a new iPhone 8 from japan and the only way to turn the shutter sound off is to delete the root file please help it's very annoying

How do i remove an old name registered to my iphone?

I bought my 13 year old daughter a used iphone 5s for Christmas.It works great. But when my daughter called my cell, it came up a different name than hers? Its probably the old owners. How do i put the phone in my daughters name? She has ATT service!

Chrome tabs closed on iphone. No option to re-open?

Woke up today, checked google chrome on my iphone, and found out all my tabs were closed for some reason. I don't have an option to re-open the closed tabs. This is very frustrating. Please, please help with this. I hope there's a way to get my tabs back instead of going through my whole history.

Why won't my parents get my a new phone?

Okay, i'm not trying to sound spoiled or anything like that, but I've had this iPhone 4s for about 3 years now. It's cracked so bad at the front top left corner that a chunk of glass is missing from the camera (I can't take front-facing pictures now, and I'm not the one who dropped it. It was a hand-me-down phone from my parents that had previously dropped it.) Its buggy and slow, and it's really hard run decent apps on. I've factory reset it three times now, but it hasn't gotten any faster. Some apps aren't compatible with it. On top of that, my parents won't trust me online with almost anything, nor will they let me buy any apps that cost money. Not even a $1.99 app. I'm frustrated with the phone, and I have enough money of my own to buy a new one, but they won't let me spend it. It's not money saved for college either, that money is in my account. What should I do? Halp!

What is a photo editing app for iPhone where I can do this?

I keep seeing people posting pictures with tumblr-looking, pixely speech bubble-type things tiled in the background, and they kind of form around the person/main object of the picture. I don't wanna ask the people posting, haha. Anyone know what I'm talking about and know an app that lets you do that? I know how to do it in photoshop but that s really extra for an instagram picture, lol.