View Railing Reference Line
To see the Reference Line on the Floor Plan: Turn on View > On-Screen View Options > Railing Reference Lines. (The arrows indicate the Railing input direction, which determines the Railing’s “left” and “right” sides - this is relevant for defining the Handrail position.)
Flip Railing
To flip the Railing to the other side of the Reference Line: Use the Flip Railing command from the context menu:
Offset Railing Reference Line
A quick way to edit Railing geometry: Select the Reference Line, then use the offset commands to edit the Reference line position (either one segment, or all segments):