If you change the pulses per unit on the Edit->MeterDetails screen, you'll have to set the maxdate back to the comdate and read the meter in again before you'll see it on your profile graph. This is to force the system to re-read and interpret (and scale) the values. Because the system is not going to read anything it has already read. That is why you need to set the maxdate back, so that the system thinks it hasn't read those values yet, and then it will read it again when you go to Tools->CommunicationMonitor and say he must read it.
(The maxdate is the bottom date&time field in Edit->MeterDetails, and the comdate is the one just above that)
(It would also be a good idea to capture a manual meter reading at some point, since counting pulses only gives consumption: it doesn't tell you the meter register reading. Once you've manually inserted one reading ON A HALF HOUR hour using Edit->MeterTotals, the system can work out any other total by adding or subtracting consumption, but the trick is getting that one total. Usually the opening reading does this function, but we didn't start properly counting at installation, unfortunately, so it's better that you physically read the meters now that we know the AMR is online and reading the pulses properly).