GUI resizing problem

Hi! I created a HUD for the PlayGui.gui in a race game using 800x600 resolution. When I change te resolution to something bigger, the HUD objetcs remain at the same place, messing up the original construiction; when I change to something smaller the border objects disappear because of the smaller screen area. I don't know what to change in order to make the HUD objects remain at the same screen location, just like the speedometer does. Does someone knows how to fix this? Thansk a lot!