All/any habits change your brain, make neural pathways stronger and others weaker. It can be as simple as my friend who started a story about going downstairs "before I brushed my teeth" (as if that was important; it was his habit and something had been so disrupting (I believe it was someone at his door) as to disturb him/the way he normally did things) to spending too much time viewing porn so you don't get other things done or don't interact with other people. Since you are complaining about the amount you view porn, I'd say you have a problem habit.

If you really want to stop, I would put the computer where others can see your use, maybe just turn the desk/chair, etc. around so you would face an open door but still be in your room. You'd have some privacy for when you use the computer for work or study but a little too openness for things that you feel need to be "secret".

There's no easy way to change such a strong habit that is associated with the primitive parts of our brain like food, sex, aggression, etc. When our limbic system gets involved, the Amygdala, changing those behaviors is extremely difficult (gambling, drinking, sexual addictions, etc.) but, possible if you work hard at it.