I'm using Magix Movie Edit Pro 18 Plus. My video is not filling the entire space which leaves a black stripe at the top and bottom of the screen. Can someone please tel me how to fix this?
Sounds like you don't have a match between your source clip format and your project settings. A right click on your clip on the time line and go to 'Object properties' to see the file information and do 'File' >> 'Settings' >> 'Movie...' (or [E] key shortcut} to see what the current project is doing. You can change the project setting there.
Top and bottom blanks would likely be 'letter boxing' -- a 16:9 aspect ratio video put into a 4:3 project.