Create drawings from models (Creo Elements/Direct Annotation) > Modify drawings > Add and modify dimensions > Modify dimensions > Modify dimension arrows and lines
  
Modify dimension arrows and lines
You can change the attributes of existing dimensioning arrows and lines in the Arrow/Line pane of the Dimension Properties dialog box. The settings and their options are the same as for the default settings, except for the following:
The broken line setting (for dimension lines) cannot be modified.
To change the direction of an arrow or re-attach a dimension,
Click the handle at the arrow to change its direction.
Click the handle at the beginning of a dimension extension line to attach it to a different geometry element.
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You cannot change the direction of arrows for broken dimension lines.