Why is my chicken all rubbery? I'm an (very) amateur chef who's just started cooking chicken. I've tried cooking chicken by boiling and frying it. 

I've managed to cook it right by boiling. The chicken is soft and tender.

But no matter what I try I just can't seem to cook it right by frying.

My fried chicken is all rubbery. I thought I'd increase cooking time to cook it more from inside. But that burnt it from the outside.

Does rubbery mean it is under cooked? Is it possible to make this rubbery-ness go away by frying it more?

(I am currently deep frying my chicken. Would frying it with less oil make a difference?)
Rubbery chicken is normally a sign that it is overcooked.

Frying is a challenging method to cook chicken, because it is very rapid, and easy to overcook the chicken.

Some of this, you will simply learn by experience, based on the typical size of the parts you are frying, and the type of breading you use.  You will learn to recognize from the pattern of bubbles and how the breading looks when it is done.

In the mean time, if you have a quality instant read thermometer, you can take a piece out and measure its temperature.

White meat should be about 158 - 160 F, dark meat about 165 - 170 F (depending on your preference).