Problem with Gui position?

I think you changed the position manually and not arithmetically, the position changes from screen to screen, if you want to put the gui in a corner to EVERY user you need to use scale and position:

Upper Left Corner:
Position: {0, 0}, {0, 0}
Scale: {0, yourSizeX}, {0, yourSizeY}

Upper Right Corner:
Position: {1, -yourSizeX}, {0, 0}
Scale: {0, yourSizeX}, {0, yourSizeY}

Lowest Left Corner:
Position: {0, 0}, {1, -yourSizeY}
Scale: {0, yourSizeX}, {0, yourSizeY}

Lowest Right Corner:
Position: {1, -yourSizeX}, {1, -yourSizeY}
Scale: {0, yourSizeX}, {0, yourSizeY}

That's it :) just remember that if you have to change a frame position which contains textlabes, textbox etc. you need to subtract the position X and Y of your frame's component in your frame's scale and position!