Note that to edit the roughness of River Section nodes (or any other node) within a river network, you must first have the river network Loaded and active.
Note: this guide refers to the River Section node in particular, however a checkbox enables the same method to apply to Bridge nodes.
The Toolbox provides multiple options for globally editing parameters. This is accessed via the fourth tab of the right-hand panel group. Click Global Edit and then 1D River Networks to access the Roughness editor tool.
Double-click to open the tool in a new pop-up window.
Select modifications to apply to the active river network. Note that checkboxes are provided to apply the modifications only where the current roughness value is equal to a specified value (e.g. 0), and to apply the modifications only to selected nodes. Un-check the box(es) provided to apply the specified modifications to all relevant nodes in the network.
Click OK to apply the modifications. Don't forget to save your network!