Default screen position upside down

[AC Question]

Hi people. A few months ago my parents bought a tablet for my sister. It's a really cheap one, a "Magnum Tech Tablet 7'' MG728iS" or something like that. The problem is that some camera apps like B612 that don't rotate, appear to be upside down. What I mean is, when you open the app and hold the tablet with the right hand, the camera is at the bottom, while it should at the top, so If you try to click the button to take a photo, the frontal camera is obstructed with your thumb. It happens with all the apps that don't support 180° rotation or landscape. Looks like the system has it's default natural orientation inverted. Is there any way to change that without downloading an app to manually force the orientation in every other app? The tablet is not rooted, but I'll do that if it's necessary (the warranty is already void because my sister received the tablet many months after it was bought). Thanks in advance.