How do i know when to use Que, Cual, and Cuales ? what is the rule for each usage please

I hope this helps. It helped me. http://spanish.about.com/cs/grammar/a/que_vs_cual.htm

A simple rule would be... Que=What Cual= Which or which one. Cuales=Plural of which (It sounds funny but it makes sense in spanish). All of them have an accent when used in a question...¿Qué?, ¿Cuál? and ¿Cuáles?. And do not have an accent when used in other instances. ¿Qué comiste hoy?-What did you eat today? ¿Cuál es tu comida favorita?-Which one is your favorite food/dish ¿Cuáles son tus comidas favoritas?-Which are your favorite foods/dishes. Saludos desde Baja California, Mexico!

Cristian: thanks as always for your simple yet effective answer. I think what confuses me (and perhaps other English speakers) a bit is that we use "what" and "which" interchangeably..."what flavor of ice cream do you want" or "which flavor of ice cream do you want" are equally acceptable grammar. When working in Spanish I try to separate the uses of Cuál and Qué as you have done above because it helps me remember the meaning of each better. But I wonder if they are also interchangeable as well? Are... ¿Cuál tipo de helado...?" and "¿Qué tipo de helado...?" both grammatically correct? Gracias, Dan

Hi Dan! Almost everytime you use Cual in a question, it can be interchange by Que and it won't change the meaning, but it doesn't apply all the way around. For example, ¿Cuál tipo de carro te gusta? can be turned into ¿Que tipo de carro de gusta?. But, when you ask "¿Cuál es tu casa?" (pointing at some houses) "¿Que es tu casa?" (This one doesnt make sense, it is asking What is your house? not Which one). So, what I am saying is that it is interchangeable at a very large percentaje of cases, but maybe not as highly interchangeagle as in English. ¿Cuáles son sus dudas? ¿Qué dudas tienen? (Almost the same question, with cual and que, but the sentence changes a bit. Do you have any questions?) Saludos!

Christian: ¡Gracias! Tu explicación es tan claro como cristal. Dan

Thanks. This helps me.

Thank you for the exchange of information. It helps.

In lesson 12.8, it says that if you want to ask "which?" you cannot use "cuál" if it is followed immediately by a noun. However, in the next lesson, one of the sentences they use is, "¿Cuáles manzanas dice que se echaron a perder?"
One of these is wrong. Which one is correct?
Thank you!

I had forgotten this rule, but interestingly enough, I just came across a pertinent example in the Travelogue course:
- No, no pueden por dos razones.
- ¿Qué razones?

The question could have also been phrased: ¿Cuáles son? 

So my guess is ¿Cuáles manzanas...? is incorrect. Anyone else?

This is my understanding: 

Que 

used in the following examples:

If you say in English which car(que auto), what girl (Que chica)

If you are selectig options or deciding

Que debo comprar? - what should I buy

Que  idiomas habla ella?- What languages does she speak

Cual  

Used with the verb ser?

Never say Que es or que son always cual es, cuales son

Cual es el mejor 

Cual es la fecha hoy

Cuales son los mejores restaurantes


You can also use cual when there is no noun e.g. 

What did he buy?
Cual compro?

What did he do?
Cual hizo


I am a learner and I leanrt this a while back I hope it helps and I would be happy if you could provide any feedback