Video editing (cropping black bars, etc.)

Actually hi to all, arose the burning question on casting videos to a cart, already bombed to be honest. Here is the video small in size and time, when playing with a computer the size naturally increases and is not noticeable, but when poured into a TG, while browsing from a smartphone video direct small with big black bars on the edges when converting and editing (through program Movavi Video Editor, Movavi Video Suite, or AVS Video Editor) did and stretched at the edges, and the filling effect did the resolution changed and I can't do anything as it is poured in a small window with a hefty frame, so it stays, apparently the horror is stupid and does not see obvious things, but napravite on the right path)
Just all in theory should be uber easy and simple as editing a picture (a function of crop - press - made - ready), but then just kind of crap, in General, tell people who live in stages what and where to poke to finally stretch for full screen video to remove these black bars....