where there are two verbs in the sentence, is there a rule about which one the pronoun is attached to.
ex Magoaste-te a fazer o que but Nos queremos atrasar-nos.
Yes, there are, @lorraineg2011 
You can read this Learning Note about it: Verb Phrases & Clitic Pronouns
Your first example (Magoaste-te a fazer…) is not relevant in this context, because the two verbs are not structurally correlated, i.e. they don’t form an actual verb phrase. Also, the clitic pronoun is actually a reflexive pronoun, because magoar is a reflexive verb when applied to oneself. So, the pronoun has to go together with magoar.
As for your second example (Nós queremos atrasar-nos), it is an affirmative sentence which does have a verb phrase. Since the main verb is in the infinitive, the clitic pronoun can be placed enclitically after the main verb or enclitically after the auxiliary verb: Nós queremo-nos atrasar. If you had any additional element attracting the clitic pronoun, it would need to appear before the whole verb phrase. For example, Nós não nos queremos atrasar.
thank you for your prompt and detailed reply.
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