How do I move the text for a dimension line from between the two arrows to outside the two arrows?
Activate it, with the dimension that you wish to apply this to selected - then drag the text from your dimension out to the left or the right as far as you would like.
Could not find "centre text between extension lines", but found that the dimension line and text are two grouped objects. By ungrouping I can select the text and move it as needed.
Another question if I may. How do I select the dimension units and make as default when drawing rectangles and other shapes. The default is decimal and I want to make it fractional.