- From the Document menu, choose Document Options, 
 then select Barlines. The Barlines options appear.
- Enter a new value in either the Heavy Line 
 Thickness or the Thin Line Thickness text box. The units are whatever 
 you’ve most recently selected using the Measurement Units command (Edit 
 menu). (The default value for barline thickness is 0.46 points.) Note 
 that this setting does not change custom barlines.
- Click OK (or press ENTER).