How do I trim the content of a video on iPhone?

Before answering this question, I'm not asking about trimming the length to cut off extra seconds. I'm asking about how to trim the area where the video is captured. For example, only capturing a certain portion of the screen instead of the entire screen. Please let me know.

If I sign into an iPad with a different Apple ID, will all my stuff be gone?

I used to use my dad's Apple ID on my iPad mini (he used it on his iPhone and an old iPad 2). Now he has bought a new iPad, told some of his technicians to transfer the data from his old one to the new one, an what he got is all the apps and data from my iPad mini (including pictures, notes etc). Perhaps it chose this iPad because it had a newer ios?
Anyways, by now I have my own Apple ID with which I can possibly sign into my iPad mini, but I'm afraid that the apps that were bought with his apple ID will be gone, pictures gone, notes etc. Is that what happens? Also, do I just have to delete my apps by hand from his new iPad? (I'm also scared to do this because I'm afraid they'd be gone on both).
Sorry for such a complicated story, but maybe there are some Apple geeks out there who can help me sort this device mess out.

Is it shady for my fiancé to have two cell phones?

So my fiancé had a Samsung Note (older version) that had a lot of issues. For his bday last year I bought him the newest iPhone. I thought he would do away with his Samsung since it was no longer serviced but he continued to carry it around. I asked him several weeks later why and he said because he had a lot of info and apps he used. It's been almost a year and he is still carrying it. To work, running errands, the bathroom, everywhere. He had everything synced over to his iPhone so I've wondered why he still carries it. Now, he just moved over to my phone plan about a month ago. When I paid our bill last week I was curious and went through his call logs. I found he called a Tracfone customer care line (the ATT log identified it as Tracfone). I called it myself to see what it was and it was to reload a tracfone account. So now I'm really questioning why he is carrying his old phone, and if he does have it hooked up to service, why would he not tell me? As I said, we just synced our phone plan so I can only see logs for the last month. I don't know how often he makes calls to Tracfone. I want to confront him but I want more evidence so that he can't try and lie his way out of it. Am I being a crazy fiancé/girlfriend or is this suspicious to you? We've been together 2 years, we live together and i had no suspicion of cheating but now I really wonder. What are your thoughts?

What is a good video editing app for iPhone?

I d really rather not use my computer for editing so don't bring that up. I'm looking for a editor that can crop the borders off videos, add efects like zooming in and out, applying filters and boosting bass but i'm desperate enouh to settle for even just one of these

What can I do about getting scammed for an iPhone 8?

I met a lady off Facebook who was selling an "iPhone 8" for 400$. It worked and such when she showed me it. I connected to Wi-Fi when I got home and I found out it's fake because it won't download apps and it doesn't have iTunes. It's worthless and I wasted 400$. Can I report her to the police? What can they do? I don't know her personally bc I found her on the market place on Facebook. I went back to message her and she blocked me!

There's water inside my iphone 6, and my screen is now black?

I didn't dunk it into water but somehow water slipped into my phone and my phone blinked for a few seconds before going black. I was in a call with a friend and when my screen went black, the call didn't end i could still hear her voice. Does anyone know how to fix it without using any tools? Will the water evaporate inside my phone, or do i have to save up for a new one?