I hope you will excuse this maybe trivial question that I haven't been able to find an answer to, possibly because I don't know how to answer it properly.
In the key of C, we know that the I-IV-V progression is C-F-G. F is the fourth note of the scale and G is the fifth one.
However in the key of, say, G the progression is now G-C-D. From what I understand C should then be higher than G. Yet it seems whenever someone is talking about the I-IV-V progression on the key of G, the C they are using is actually an octave lower, similar to the C of the I-IV-V progression of the key of C!
Why does this happen? Does this mean that you can actually use a chord from any octave in this progression?