TL;DR: Latin words ending in -que should be accented on the syllable before -que only if that syllable is (or has become) heavy; otherwise, the word should retain its original accent. If this sounds new to you, that’s probably because you’ve been following Allen & Greenough and other nineteenth century scholarship.
The rules of accent in Classical Latin are usually very simple. Almost all words follow the formula of the ‘Penultimate Law’, which states that the accent in multiple syllable words falls on the second-last (the penultimate) syllable if this is of heavy quantity, and otherwise on the third-last (the antepenultimate).
But the enclitic –que (and the other enclitics, –ve, –ne, –ce) complicates these rules.