You can set the direction of dimension text to be automatically determined when dimensioning parallel lines. Normally when you dimension parallel lines, the default dimension direction of Parallel means that the dimension is measured in the line defined by the two vertices nearest to the reference points you clicked. On the other hand, when the automatic direction mode is activated, the default dimension direction is switched to Horizontal, Vertical, or Perp to and the parallel lines are dimensioned accordingly.
For dimension direction settings,
1. Click File > Settings > Default Settings
2. Expand Annotation > Dimension > Auto Placement.
3. Double-click Direction.
The Direction mode specifies the level at which automatic directions are set. The three options are:
All
Automatically selects the dimension direction (Vertical, Horizontal, or Perp to) when dimensioning any parallel lines.
Ver&Hor
Automatically selects the dimension direction (Vertical or Horizontal) when dimensioning vertical and horizontal parallel lines only.
Off
Disables automatic direction selection.
One exception occurs when dimensioning collinear elements. In this case, the default direction will be Parallel for both the All and Ver&Hor direction modes.