Hi.

I do not own a UV-82 Hp, but I do have a UV- 82 and I believe they use the same chip set.  If I understand your question correctly, I think you're saying you'd like to be able to toggle between High and Low power while on the same memory channel.  This won't happen.  I'm pretty sure the radio will automatically revert to whatever power level that was set when that channel was programmed.  If you want to have multiple power selections on the same channel whilst in Memory mode, I think your only option is to separately program the same channels  / frequencies in with the various power settings you want.  To change power you will have to go to the memory location that has the desired power level setting pre-programmed.

Changing the power setting "on the fly" only works in VFO mode.  This is pretty typical for Baofeng / Pofung radios.

73 de Ray, AE6H