I just bought the 2014 Nissan altima but I don't like it and want to take it back for the 2015, am I being picky and ungrateful?

yes picky and ungrateful, especially if your mommy or daddy bought you a new car. most people don't have nice new cars for free. But if you actually bought the car yourself with your own money, then you just picked bad timing and or did not research the fact that a new redesigned model was coming out. Sounds like the dealer also screwed you by not telling you a new model was coming out soon.

No. It's your choice.

Don't expect to get back what you paid for the 2014 though.

It is your money, so take the car back and see exactly what the dealer can do for you. They are going to empty your pockets of cash for the change, if you are ok with this ? then you have a 2015 car.

No just showing bad judgement and indecision. It's your money, expect to wave bye bye to a good chunk of it.

No you're just weird.