what if i want to increase the voltage without increasing the current
The Formula, called Ohm's Law is Amps = Volts/Resistance
If Voltage is 110 and Resistance is 10, then Amps, or current, is 11.
So, if you bump up the Voltage to 220, and you want to keep the Amps the same, you'll have to also double the Resistance to 20.
Usually, you want to increase the Amperage, as some appliances, like Air Conditioners, can run on 220 Volts. To do this, you have to DECREASE resistance, by adding a second wire or one that can take more amps.