1) In the Document Options you can specify the Default alignment of syllables:
Document Options > Lyrics
2) You can specify a different alignment for a specific syllable:
Lyrics menu > Adjust Syllables
Click on the note.
A handle appears on the syllable.
If you have several verses on that note, a handle appears on each syllable belonging to the note.
(Another handle appears above the syllables)
Context-click on the syllable's handle.
In the context menu you can specify the alignment for that particular syllable.
3) You can change the notehead with a sub-tool in the Special Tools Tool:
the Note Shape Tool.
When you are in the Note Shape Tool, click on the measure.
A handle appears on the notehead.
Context-click on the handle.
In the context menu, choose "Edit...".
In the dialog box Notehead Settings, click the button "Select..." to choose another notehead character.
You probably want to consider one of the characters #87, #135, or #221.
Finale 2011c, 2012c and 2014, Mac OS X 10.8.5, Dolet 6.4 for Finale, Finale user since 1996