Buenas tardes, tengo un problema *** la App Store trato de descargar aplicaciones totalmente gratuitas y no me deja me exige poner un método de pago, no me permite cambiar la opción.

I try to download totally free applications and it does not let me, it requires me to put a payment method,

If you want to make purchases or update / download apps, including free apps, you need to update your payment method or add a new one. 

See also the following Apple articles:

Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

Add money to your Apple ID balance

Add money to your Apple Account balance – Apple Support (UK)

If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

Click here for more support and assistance.