It's because you set the object on the global layer to global so every time you switch layout it's doing the following :
Go to Layout 2 > Load Global Layer with Global Object 1
Go to Layout 3 > Load Global Layer with Global Object 2, Global Object 1 remains as it is global
Go to Layout 4 > Load Global Layer with Global Object 3, Global Objects 1 and 2 remain as they are global.
If the HUD elements are going to be updating between layouts and it's important that they persist then just make every object on the HUD a global object. If you want to do it with a layer then do not make the objects on the layer global, only the layer.