crr1612

ok guys, so i replaced have an aftermarket head unit with only 4 speaker outputs, aftermarket front 2 speakers and aftermarket rear 2 speakers. i finally got my rear speakers installed after having the front installed for a long time. then, the rear right speaker went out, so i pulled it out to check the wiring, it works but i didnt put it back in. then i was driving today and realized that the right side door speaker wasnt working and after a few seconds of anger realized it is probably because the rear and door speakers are hooked up in series. so i thought it wasnt a big deal. then i remembered that i have to keep my fader set a little towards the rear because my backs speakers have so little power. i think it is because they are in series and not parallel. what do you guys think? also, you think i should hook up the rear 2 speakers in parallel, or the difference in impedance would do more harm than good? thanks in advance