How Do I Change The Instrument Label Position?

I want to change the instrument label to the left, put when I choose that option the instrument label doesn’t change in the score.

It’s a bit unclear, I grant you, but the alignment of staff labels is actually changed by editing the alignment of the Staff labels paragraph style, which you can do in Library > Paragraph Styles.

You can see a labelled example of the different paragraph styles that are used in staff labels on this page: