The number of turns of the coil of a moving coil galvanometer is increased in order to increase current…

Current sensitivity $=$ Voltage sensitivity $\times R$

If current sensitivity is made $1.5$ times, then $R$ also increase $1.5$ times.

Hence, voltage sensitivity $=\frac{1.5\times \text{ current sensitivity }}{1.5\times R}$

$=$ no change.