Edit instruments

When I edit the instruments (Create -> Instruments) of a template, the name of a random instrument will appear in the top left of the page. When I delete the name of the instrument from the top left, the name in front of the corresponding staff is also changed.

For example, I start with the Chamber Orchestra template.
Then using 'Create -> Instruments,' I add a piano part (on the very bottom). Then, if I delete an instrument, say "Bassoon 2", a text box with "Piano" suddenly appears just to the left of "Flute 1". Then, when I try to delete the "Piano" from the top left, the name next to the piano staves disappears.