1. Autodesk Inventor
Bend Line Change

2. For change a bend line in 2D Drawing of Inventor Sheet Metal, can do with editing style Editor in your Template of IDW/DWG.
Before
After
Step 1
Create a new drawing (IDW/DWG)
Step 2
Go to menu “Manage”  Click “Styles Editor”
Then Create a new layer:
Bend Centerline Down (Linetype Dashed)
Bend Centerline Up (Linetype Continous)
Don’t forget to save after create new layer.

3. Step 3
Still on Style Editor.
Go to “Object Defaults” or Active standard we want to set.
Then find out an object type:
Sheet Metal Bend Centerline (+)
Sheet Metal Bend Centerline (-)
Set the layer:
Save, and Finish for setting.
We can trying for make a flat pattern.