I could find this in the help files, so I hope someone on here can help!!!

I finished 1 composition, but when it has the instrument name on the left on every stave, for one instrument it seems to have jumped to the right! And on some pages it's over top of the stave so you can't read the notes! It's only 1 instrument that it's happened for, and I can't select it to drag it back. My friend suggested copying and pasting everything into a new document, which I don't really fancy doing, because it's 21 pages long.

see if you can hide it (right click hide object) and then type a new one where it should be using plain tetx?