Are you talking about the app shortcuts row like the icons for YouTube, Chrome etc.. on the right side like in this picture? If you can't find the option to change the home screen, there may not be a way. They should rotate depending on the tablet orientation to bottom when in portrait mode.
It may be set there as a widget on the home screen, those you can move around with a long press on the screen.
That changes depending on the orientation of the tablet.