The best way is to select all of the measures and double click the volta in the palette. If the volta is already there and you insist on changing its size, double click it, the select the the end box for the direction it needs to be enlarged and press shift + an arrow to change its size.
Comments
The best way is to select all of the measures and double click the volta in the palette. If the volta is already there and you insist on changing its size, double click it, the select the the end box for the direction it needs to be enlarged and press shift + an arrow to change its size.
In reply to The best way is to select… by mike320
Thank you.
See https://musescore.org/en/handbook/voltas#change-volta-measures