To edit the Staff Name, go to

ScoreManager > Instrument List

Highlight the Congas staff, and click the button “Full Name…” to edit the full Staff Name (= the Staff Name in the first system).

Click the button “Abbr. Name…” to edit the abbreviated Staff Name (= the Staff Name in all the other systems).

To set the music font in a staff:

Staff Tool.

Double-click the staff.

In the Staff Attributes, in the pane Independent Elements, go to Notehead Font, and click the button “Select…”.