How can I expand scrollrect through text?

I have a scrollbar which scrollrects a GUI text vertically, but as I add more text to the textbox, the textbox doesn’t automatically expand its height as more information is added to it, so it scrolls down to a cut-off point.

How would I fix this so it auto-expands?

I had the same problem some time ago: Scroll rect items placed outside the content area - Questions & Answers - Unity Discussions

Basically you need to find the gameObject called content in under the scroll rect and resize it.