the CPU voltage settings are changing automatically. Is this normal?
Yes it is normal.
Due to silicon lottery, some processors can withstand higher voltage and overclock more than others. Kernel Adiutor intelligently lowers voltage if it figures that your processor cannot handle it. It is possible that the processor in your device is slightly inferior so kernel Adiutor is reducing voltage to prevent damage to your processor.
My suggestion would be to first change the voltage for lower clock speed and progressively move on to change the voltage for higher clock speeds, first for the small cores then for the big cores. ( In simple words, change voltages for first row first . Then change for the second row. And so on )
If kernel Adiutor makes any changes then for the lower clock speeds in voltage, let it be. After you have finished doing settings across CPU , GPU, voltage, I/O , etc, then go to profiles, tap the + button and save current profile as new profile. Then tap the three dots on the new profile and set it to be applied on Boot.