I have the NAV/CD/Satellite option on my car which by the way, I could have foregone the NAV. The manual talks about the CD changer and switching to the next disc. The buttons have Disc 1-5. I have tried to add other discs, but it seems like it holds just 1 disc. Does anybody know if it holds 1 disc or 5? If it holds more than 1 disc, how do you get them in? Thanks.