Go to File, Drawing options:
For one drawing,
draw_arrow_length - sets length of leader line arrows
draw_arrow_style - closed, open, filled
draw_arrow_wdith - sets width of lead line arrows
to edit for all following drawings, you can edit the active drawing file and click the save icon near the top.
to edit future drawings, save this as another name (i.e. Drawing_Std_2013_09_19.dtl) then open that file and apply it as need to future drawings.