Change multiple bindings at once

This feels like a stupid question. But here goes.

How do I change (for example) the source of several bindings at once. I want to change them to a different port.

If I right click on the existing input port and copy, and then paste into the next row down, then it pastes a whole new binding, not just change that field.

Multi-select again highlights rows at a time, not columns.

thanks,
Al