Use the Width and Height settings for Canvas to set or change the size of the design area. Click Apply 
to use the new settings.
Width
Set the Canvas Width from 20mm to 1000mm. The initial size is 100mm.
Shortcut
-
Keys: Alt, V, W
Height
Set the Canvas Height from 20mm to 1000mm. The initial size is 100mm.
Shortcut
-
Keys: Alt, V, HE
Apply
Use Apply 
to use the new Canvas size.
Shortcut
-
Keys: Alt, V, A