Hi I'm a bit confused as to which cells should be ticked/unticked.

For instance, in the log sheet, row 11 has a serial number of 006 and row 15 has a serial number of 0064.
If i double-click row 11 and enter 0064 which row should have the tick be assessed on?

You say the active cell so, based on that, row 11 would be ticked/unticked as a result of finding 0064 or row 15?