2d backgrounds - filling all screen sizes

Hi, I created a few backgrounds for my 2d game and adjusted them to fill the screen in the scene mode; but, when I test it on my mobile device or in game mode under different screen settings, there’s always a little empty space on the x axis. I’ve looked around for hours to find out how to fix it and I’m getting nowhere. It seems so simple but I can’t find some basic information on the proper way to do this. Right now, I have a gameobject with children that contain the sprites, which make up each background. I’ve included screenshots of the camera setup, the background in game mode, and the background in scene mode. I know this is basic but I’m a basic boy. Thanks!

Try to make your game view window smaller on the x axis.