Why is the text size not remaining the same on a billboard GUI - I used scale?

I used scale for the size of the textbox, I don't understand why the text is scaling down when you get close to the textbox.

It's very distracting, as my game is a fighting game, and I can't have the text changing size constantly during fights.

I am using the text for a HP bar.

Here are two images which show the size properties used and what is happening:

https://imgur.com/a/eBrhh