OK heres the skinny on voltage on the Buzz
1. When you are setting the voltage the unit is Unloaded , this will allow you to set it above 6 Volts BUT when you put the atomizer on it the batteries will LOAD down ! that is why we spec a 3.6 to 6 volt range , this is the USABLE range !
2. anything from 3.6 to 6 volts will be fully regulated , beyond 6 volts it will NOT be a stable voltage ( it will try to maintain a .5 volt difference across the regulator ABOVE 6 volts )
You do need a voltmeter to really know what voltage you are at , you can get an idea by pointing the led at a white piece of paper and noting the difference between the Red LED and Blue Led , the Blue led is the output LED as it gets brighter as the voltage is increasing .
LR atomizers are NOT recommended ( and not needed ! ) they will try to draw a higher current.
The Buzz circuit is NOT designed for LR atomizers , to compensate it will lower the voltage to the atomizer so it stays in its SAFE zone for operation ( this is one of the protection circuits kicking in ) It will work But is NOT recommended.
I hope this clears things up ? If not ask away