In star trek, how does the crew change different attributes with only two buttons. In the films and series, they change: intensity, width, frequency setting, security clerance (authorisation to fire), self-fire (when wesley uses it as a decoy), self-destruct. How can this be when there is only two buttons, also, how is this shown when again, there is only a single stat indicatior bar (strip atop the phaser)
It's not really made that clear. It seems that those who've been trained on phaser operations have been told how to access the additional features.
The TNG Technical Manual has some additional info but no real answers.
There's also some info on how to cause an explosion (basically, by dickering with the safety interlock).
As a result of the basic physics required to produce a phaser discharge, an undesirable but unavoidable process exists, namely that of phaser overload. The accepted methods employed for energy storage, flow, control, and discharge allow for an amplified rebounding to occur from the storage cell to the prefire chamber, and simultaneously back to the storage cell.
While the total energy within the system remains the same, the flow pressure is elevated during the rebound, to the point where the storage cell cannot reabsorb the energy fast enough. The barrier field will be reinforced during this buildup, effectively preventing normal discharge through the emitter.