To change the Cursor’s position, either press LMB with the Cursor tool selected,
or Shift-RMB with any tool selected. You can also change the “Location X/Y” fields
in the View tab of the Sidebar, in either relative coordinates (0 to 1) or
In both cases, the lower left corner of the image serves as the origin (0, 0).
You can press Shift-C to move the Cursor to the center.