Customize the settings

"I got" is ok, but not the best choice.  If by "got" you mean that you own a new cell phone, it would be better to say, "I have a new cell phone."  If you mean that you obtained a new cell phone, say, "I have gotten ..." [Amer.English],  or "I have got ...." [Brit.English]

"Customize" is correct.  However, another possibility is the verb "personalize".  "Personalize" is a good word to use when the the changes are truly personal to you.  For example, if you are going to adjust the settings so that the ring tone is your favorite song; or if you are going to put your child's photograph on the welcome screen, you could say, "I should personalize the settings."  For things that aren't particularly personal to you, you can use the word "customize."  For example, if you are going to adjust how long the screen will stay illuminated after you press a button, that is not very personal to you, and the word "customize" is fine.