-snip-
Edit: So are you saying you want the bars to be in a fixed position from the player? In that case you'd have to scale the distance based on the distance from you to them. Right now, the bars are being placed in a fixed location; they're not moving, but look like they are because of the increased size of the player. If you measure from the right end of the bar to the right end of the screen on both screenshots, you'd get the same value.
So what you need to do is find the distance between you and the target, then scale the x pos based on how close or far someone is. If that makes sense.