Changing printed measurements

Afer drawing two curtains 20’ apart on a stage plan I find on labeling it up that it shows a measurement of 19’- 11 7/8" Apart from why this should happen, is there any way to override the printed measurement ? One could sometimes finds it quicker to do this anyway to avoid redrawing a whole plan

There are various reasons why the dimension might not show what you expect, ranging from an actual error in the model to snapping the ends of the dimension to different vertices than you intended. However, as a fudge you can edit the text: right click on the dimension, select Edit Text, and the dimension’s text will change to an edit box. Note that in SU 2017 the text will now display as red because the dimension isn’t showing the actual size of the associated object.

Thank you so much that is just what I wanted to know. Good on 17 seeing the snag

… and you can change the units via: Window > Model Info > Units