Programs in app store

please help me.

every program i want to download even i write free program, it doesnt give me the option to download free.

for examp i want to download snapchat that every body got it for free but to me is asking purchases. Even games is asking the same thing.

IPhone is not giving me anything for free. what is going on, did i touch anything that shouldnt in iphone? I hate this situation is makine me change from iphone to android.

thank you in advance

Eva