/serversigns select

Issuing ServerSigns administration commands usually then involves right-clicking a ServerSigns controlled block in order to specify which sign or block should be updated. Alternatively, you can issue this command, right-click the sign, and then all additional future ServerSigns administration commands will be assigned to that block or sign automatically.

This command is actually a toggle, so repeat exactly the same command to unselect the currently active sign. This will return you to being prompted to manually right-click signs/blocks when entering further ServerSigns administration commands.