How do I Move UI properly ?[Newbie]

I would like to make simple slide menu and simple code but every time I get current Posx from
Update Method , I had got multiple current number of positoin of x
example
Update
//get curent of x Pos
float origin = GroupPanel.transform.localPosition.x;
Debug.Log (origin);
//add new Position
GroupPanel.transform.localPosition = new Vector3 (origin + -676f,0,0);

each column width 676f
If I touch "next" by one time, just one time!
[right to left]
-676f
-1352
-2028
-2704
-3380
this...

How do I Move UI properly ?[Newbie]