Answer : The correct answer for both the fill in the blank is, increases.
Explanation :
Formula used :
1)

B = strength of magnetic filed
N = Number of loops
I = current in the wire
= magnetic permeability

The more the number of loops in the solenoid more will the strength of three magnetic fields.
2) Also according to Ohm's law:
Voltage is directly proportional to current:

With increase in voltage the the current will increase which in return increase the magnetic field in the solenoid.
So, the correct answer for both the fill in the blank is, increases.