In this Handrail the Angle section for the top rail is "open side" up but should be facing down instead. Is there any way to rotate the Angle 180 degrees so that the open side is facing downward?
By default, Angle sections are placed "open side up" even using the Place Beam tool.
However, you can change that member's orientation after the fact by using the Building Element Info tool as shown below. Note that you may also need to change the Placement Point so that the top member is properly aligned with the railing.
Note: You can also permanently change the rotation of the member based on its assigned Family and Part as outlined in this wiki: https://communities.bentley.com/products/building/building_analysis___design/w/building_analysis_and_design__wiki/39452/place-timber-floor-roof-joists-at-a-spacing-member-rotation