I have one 2/1 channel Alpine amp with one 10" sub. if i wanna more bass, should i replace the current one with a 12" or get another 10"??

here are the specs for my amp:
Max power 225x2 4ohm; 600x1 4ohm
12v RMS power 70x2 4ohm; 120x2 2ohm; 240x1 4ohm
14.4v RMS power 100x2 4ohm; 170x2 2ohm; 340x1 4ohm

btw, what do the readings of 12v and 14.4v mean and how can i find out on which setting i am running?