You can find options for the project-wide appearance and position of player labels on the Condensing page in Engraving Options.
The options on the Condensing page allow you to set precise distances between player labels and the staff and other items, choose whether they erase their backgrounds, change whether player numbers are separated and appended with periods or commas, and change the text shown for “to” and unison indications.
The options are accompanied by diagrams to help you visualize how they affect the appearance of your music.