Wait what?
Are you talking about your screen resolution, how it sometimes looks like this? (this is just an example, not a tutorial)
the black bars on the sides, are you talking about those black bars on the sides in the youtube video format display?
If so, it means you have a monitor that doesn't have a suitable widescreen length. Making your screen capture video looking square, thus making it look like that. There are ways to solve this: One,
buy a HD widescreen monitor to make your screen capturing life easier. Two, go to your
screen display settings and change the resolution if your computer can provide that. And Three, screen capture the video and
stretch the width of it making it to fit the widescreen size (but it looks funny, in my opinion).
idk if thats the answer you are looking for, cause I took a quick look at your channel and your videos seem to be okay and not having a problem like that at all.