You can nudge one or more fixtures along a pipe, straight truss or on the floor. (Not curved truss.) See Nudging for basic information on nudging objects.
Note: The nudge distance is the Snap Interval value defined in the Document Options > Hang Structure Settings tab. See Hang Structure Settings tab.
Tip: You may also nudge fixture(s) by half the Snap Interval distance by pressing and holding SHIFT and ALT, and then pressing the ARROW keys.