Fullscreen problem

Hello everybody!
I hope someone here could help me, because I really don’t know what to do anymore, and it’s driving me insane!

The problem is simple : I want my game to be displayed fullscreen.

If I do this

Graphics = new GraphicsDeviceManager(this);
graphics.PreferredBackBufferWidth = 1280;
graphics.PreferredBackBufferHeight = 720;
graphics.IsFullScreen = true;

The game is displayed fullscreen, but everything is shifted to the left of the screen. For example, if I have a picture, a small part of it will be cut to the left.

Before I solved the problem by using
graphics.HardwareModeSwitch = true;

Unfortunately, now I have made a cross platform project, and if I do that, when the game is fullscreen, nothing is stretched anymore.
For example if the game resolution is 1280x720, and the computer’s resolution is 1920x1080, the window will be 1920x1080 but everything inside it will be 1280x720.

Someone has a idea of what I could do?